Paccar Exhaust Gas Pressure Sensor? Trust The Answer

Exhaust gas temperature sensors are becoming increasingly popular in modern vehicles thanks to increasingly stringent emissions legislation. And because they’re a high-failure part, they’re also becoming an increasingly popular repair option. Here we explain what the exhaust gas temperature sensor does, why and how it fails, and how to replace it so you can take advantage of this fast-growing service opportunity with a quality, proven repair.

What is an exhaust gas temperature sensor?

As the name suggests, the exhaust gas temperature sensor measures the temperature of the exhaust gas. This information is then relayed back to the engine control unit or ECU where appropriate action is taken. On petrol engines, its primary role is to protect key components from the higher temperatures that are common in downsized engines. So if the sensor detects temperatures that are too high, the control unit lowers the temperature, for example by lowering the boost pressure in the case of the turbocharger. or to increase the amount of fuel injected for the catalytic converter. On diesel engines, exhaust gas temperature sensors are also used to monitor the temperature of the diesel particulate filter (DPF) to set the right temperature for regeneration and reduce harmful emissions. It is not uncommon to have three or more sensors fitted to the exhaust; one before the turbocharger, one before the DPF and the third after the particulate filter.

How do exhaust gas temperature sensors work?

There are two types of exhaust gas temperature sensors; one with a positive temperature coefficient (PTC) sensor element and the other with a negative temperature coefficient (NTC), the only difference being how they measure temperature. The NTC element has high resistance at low temperatures and low resistance at high temperatures. In other words, its resistance decreases with increasing temperature. Whereas with a PTC element, the most common type, the resistance increases with temperature. In both cases, a temperature is assigned to the resistance in the ECU and appropriate measures are taken.

Why do exhaust gas temperature sensors fail?

One of the most common causes of exhaust gas temperature sensor failure is excessive temperatures – in some cases over 900°C – which they protect other components from. As with all wired sensors, internal connections can become loose from excessive vibration, and bending or twisting can cause the wire to break, making them particularly susceptible to damage when replacing other components in the exhaust system. These, along with contamination from other liquids such as oil or antifreeze, can all affect the sensor’s response characteristics, causing it to drift out of tolerance and provide inaccurate readings.

What are the symptoms of a faulty exhaust gas temperature sensor?

A defective exhaust gas temperature sensor can negatively affect a vehicle’s aftertreatment system and lead to the following symptoms:

Check Engine Light: If the ECU detects a problem with the sensor or signal, the check engine light will illuminate.

Reduced fuel efficiency: If the sensor reads incorrect voltages, the DPF regeneration process can take longer, resulting in increased fuel consumption.

Unnecessary DPF Regeneration: Faulty sensors can also lead to unnecessary regenerations and cause inconvenience to the vehicle owner.

Failed emissions test: An incorrect reading can cause the EGR system to malfunction without triggering the check engine light. This can cause an emissions test to fail.

Component Failure: Increases in exhaust gas temperatures can also contribute to the premature failure of other exhaust or internal engine components.

How do I troubleshoot an exhaust gas temperature sensor?

To diagnose a faulty exhaust gas temperature sensor, follow the steps below:

Do an electronic test and read any trouble codes with a diagnostic tool.

Inspect the connectors for signs of corrosion or loose connections.

Check the wiring for breaks or damage that could cause a short to ground.

Inspect the sensor for a build-up of contaminants and, if necessary, wipe with a clean, dry cloth.

Use a separate IR meter to test the sensor and compare the readings to live data obtained with a diagnostic tool. Run the engine so that the exhaust gas temperature rises and compare the readings.

With the vehicle ignition switched on and the connector on the EGT sensor unplugged, measure the voltage at the connector of the sensor – it should be 5 volts. If not, trace the wire back to the controller and check the supply there.

What are common exhaust gas temperature sensor trouble codes?

Common error codes are:

P0544: Exhaust Gas Temperature Sensor, Bank 1, Sensor 1 – Circuit Malfunction

Exhaust gas temperature sensor, bank 1, sensor 1 – circuit error P0546: Exhaust gas temperature sensor, bank 1, sensor 1 – high input

Exhaust gas temperature sensor, bank 1, sensor 1 – high input P2033: Exhaust gas temperature bank 1, sensor 2 – circuit high

Bank 1 Sensor 2 Exhaust Gas Temperature – Circuit High P247A: Bank 1 Sensor 3 Exhaust Gas Temperature Sensor – Out of Range

Bank 1 exhaust gas temperature sensor, sensor 3 – out of range P0549: Bank 2 exhaust gas temperature sensor, sensor 1 – circuit high

Exhaust gas temperature sensor, bank 2, sensor 1 – circuit high P2031: Exhaust gas temperature bank 1, sensor 2 – circuit failure

Note that by design, PTC sensors will continue to relay misinformation to the ECU without setting a diagnostic trouble code.

How do I replace an exhaust gas temperature sensor?

If the exhaust gas temperature is faulty, it needs to be replaced – just follow the best practice tips:

You can replace the sensor if the sensor is not matched/programmed to the vehicle, the ecu will think the old sensor is still fitted, if it is not fitted correctly this can cause further problems and result in your DPF blocked.

The exhaust gas temperature sensor is a thermistor element mounted in cement to protect against vibration and housed in stainless steel to withstand extreme temperatures of up to 900°C.

Changes in temperature lead to changes in the resistance of the sensor, which are transmitted to the ECU as a voltage.

In a TechAssist bulletin, Lucas explains that these sensors protect key exhaust components from overheating and help control emissions.

They are also used in multiple combustion control processes in diesel and gasoline engines, including selective catalytic reduction (SCR), turbocharging, exhaust gas recirculation, and DPF regeneration.

A faulty sensor reporting incorrect voltages can result in poor fuel efficiency as DPF regeneration takes longer to complete.

DPF regeneration

The DPF regeneration process can affect drivability.

Faulty exhaust gas temperature sensors can result in unnecessary regenerations causing driver inconvenience.

Lucas says some sensors are harder to diagnose than others.

PTC sensor failures are often misdiagnosed as DPF problems because they continue to function after the failure, sending incorrect signals to the ECU that interfere with the DPF regeneration process.

NTC sensors are more likely to trigger the check engine light if they fail.

Extreme heat is often a cause of failure over time.

According to Lucas, a common problem with all wired sensors is that wires can break, especially when subjected to severe twists and turns.

They are also easily damaged when replacing other components in the exhaust system.

For this reason, Lucas recommends replacing the exhaust gas sensors at the same time as the exhaust system or components such as the DPF or KAT.

Exhaust gas temperature sensors have many features that help them withstand vibration, but they can still take their toll over time.

Installation instructions 1. Make sure that the exhaust system has cooled down before you start work. 2. Handle the exhaust gas temperature sensor carefully, dropping the component may cause invisible damage to the cement securing the thermistor. 3. If the sensor has a thread, clean the thread in the exhaust pipe with a cleaning tap. 4. Apply copper grease to the sensor threads only. Although some sensors are pre-greased, additional grease will prevent thread galling and reduce friction, which could result in over-torque (especially with stainless steel threads). Torque wrench to avoid over-tightening and/or damaging the wire. 6. Start the engine and check that the exhaust system is working properly. A reset of the ECU may be necessary.

With just 100 part numbers, Lucas Electrical’s range of exhaust gas temperature sensors covers over ten million vehicles on the road.

To learn more about and view Lucas Electrical’s range of exhaust gas temperature sensors, select “More Details” below.

The diesel particulate filter warning light is an indication that this particular filter will need to be cleaned or replaced soon to avoid the car going into limp mode. This is a common challenge that diesel engine vehicle owners must learn to deal with before the problem occurs.

The exhaust gases of a vehicle inevitably become sooty over time due to constant combustion. The particulate filter is designed to remove soot from the exhaust. However, the filter can clog over time.

Ignoring soot formation can be harmful in the long run. One of the early symptoms to deal with is the DPF warning light. Find out what is triggering the light and how to fix it in the sections below.

What Causes Diesel Particulate Filter Warning Light?

The main cause of the diesel particulate filter (DPF) warning light is a clogged particulate filter. The warning light indicates that the onboard computer system has detected excessive soot buildup in the particulate filter, which is likely to trigger limp home mode.

Another cause for the DPF warning light to come on is a faulty pressure or temperature sensor. If this component is not working, it will send incorrect signals to the on-board computer system, which may unnecessarily trigger the DPF warning light.

However, excessive soot build-up in a vehicle’s particulate filter is the main reason why the DPF warning light comes on.

How do I fix my diesel particulate filter warning light?

If a vehicle’s diesel particulate filter becomes clogged with too much soot over time, there is a risk that the vehicle will go into limp mode. This can be a serious problem for your vehicle so you need to get it fixed as soon as possible.

The solutions below will help you understand how to fix the diesel particulate filter warning light problem in your car. Make sure to carefully implement the recommended solutions below to clear the DPF warning light.

Drive past 40 mph to trigger regeneration

The most common fix for the DPF warning light indicator is to drive above 40 mph. If you do this, get out of the busy region of your city and find a long stretch of freeway.

Once on the road, cruise at a brisk 40+ mph while monitoring the engine to keep it at around 2500 rpm. This automatically triggers an active regeneration, which in turn increases the temperature.

At this point, the clogs are converted to gas and exit through the exhaust. Be sure to stretch the car for up to 15 to 30 minutes. After that, the DPF warning light should go off.

Apply DPF cleaning additive

An alternative approach to cleaning a clogged DPF filter is to use a DPF additive. You can get a good DPF cleaner for as little as $13-$26 and put the solvent in your vehicle’s fuel tank.

When applying the amount, be sure to follow the manufacturer’s recommendation. After that, start the vehicle and drive for about 15 to 30 minutes.

The DPF warning light will turn off automatically within 30 minutes of driving if the additive is circulating in the fuel system. So instead of asking, “How long can you drive with the DPF light on?” It’s best to fix the problem right away.

frequently asked Questions

Q: What to do when the particulate filter light comes on?

The particle warning light is something to be aware of. Don’t panic because you can solve the challenge in a moment. So if the particulate matter warning light comes on automatically in your car, drive your car onto the motorway immediately.

Once you’re sure you have a clear road to drive non-stop, stretch the car by driving about 15 to 30 at a speed in excess of 40 miles per hour

Q: Is it ok to drive with the DPF light on?

Driving with your car’s DPF light on is not ideal. Although the car may not have any problem moving on the road, in the long run the problem can be serious. If you completely ignore the DPF light, you risk your car’s filter building up enough soot to clog the filter.

Once soot build-up reaches a certain level at which the filter becomes clogged, your car will automatically switch to a limp home mode to protect the engine from damage.

Finally, limp home mode changes the proper functioning of several components in your car to ensure the engine is protected. In this case, you may not be satisfied with driving a car.

Q: What does the diesel particulate filter light mean?

The diesel particulate filter warning light in Nissan Navara is the same as the diesel particulate filter warning light in VW Golf.

When this light comes on in a car with a diesel engine, it means that the amount of soot in the car’s exhaust is so high that it can trigger limp home at any time.

Don’t panic when the light comes on in your car. You can fix the problem within minutes. Just drive out of the busy region of your city onto a highway where you can drive at high speeds.

When you get onto the freeway, accelerate and drive at speeds in excess of 40 mph for about 15 to 30 minutes. As soon as you do this, the temperature rises and the vehicle’s filter is regenerated; then turn off the warning light.

Q: How do I clean my DPF filter myself?

Manually cleaning your vehicle’s DPF filter is another way to eliminate soot build-up. All you need is a good DPF cleaner with an additive. The DPF cleaner neutralizes the soot deposits that clog the filter.

Once you’ve gotten a good DPF cleaner, turn off your car and open the gas cap. Then pour the recommended amount of cleaner into the tank and replace the tank cap. After that, start the car and drive around for about 15-30 minutes to get the DPF cleaner working effectively.

Once you finish using the DPF cleaner and drive for the recommended amount of time, the warning light should go out on its own. Then you can return to normal everyday driving. So if your car’s diesel particulate filter warning light is flashing, make sure you get it fixed as soon as possible.

Q: How much does it cost to clean a diesel particulate filter?

Cleaning a vehicle’s diesel particulate filter (DPF) is an important task. Only experienced DIYers can do the job perfectly without damaging the filter. Therefore, you need to contact a professional auto mechanic to get the job done if you are not sure if you are doing it well.

The cost of cleaning a diesel particulate filter is around $85-$100. However, if the filter is completely blocked, you may need to budget for up to $300.

If you are considering whether or not your Nissan X Trail Diesel Particulate Filter warning light needs repairing, please be aware that failure to do so can trigger limp home and pose a serious challenge to your vehicle in the long run.

last words

The essence of understanding what to do when the diesel particulate filter warning light comes on cannot be overstated. The exercise is likened to a life saver for your car; Otherwise, you risk the car going into limp mode.

The cause of the DPF warning light display and the solution have been revealed above. Pay attention to these factors to avoid complications.

If your car’s DPF warning light is already tripping, simply apply the recommended solutions in this article as soon as possible. However, if you are not sure that you can fix the problem perfectly, please contact an auto mechanic to help you.

Learn more:

Discover the warning signs and symptoms that indicate a bad or clogged diesel particulate filter and how much it costs to replace it.

If you drive a diesel vehicle, you may have heard of the Diesel Particulate Filter (DPF) but may not be aware of its purpose. In fact, you may never find out what this important part is until you try to determine if your vehicle has a bad Diesel Particulate Filter (DPF). But how can you tell if your DPF is clogged or bad?

When the DPF filter is blocked or clogged, the engine will deteriorate and a check engine light will often appear on your dashboard. It can also lead to higher fuel consumption and create a difficult starting situation. In addition, you can also detect strange smells or turbocharger problems.

In this guide, we assess the symptoms of the clogged DPF filter. We’ll also show you why it’s important and discuss how much it costs to replace it.

Symptoms of a bad or clogged Diesel Particulate Filter (DPF).

1. Check engine light

The first common sign of a bad DPF is a check engine light on your dashboard. The diesel particulate filter uses sensors to measure the pressure and temperature before and after the DPF filter. If the pressure is not correct, the engine control unit will illuminate the check engine light on your dashboard.

If you see a check engine light on your dash, you will need to scan the trouble code memory with a code scanner to find out what’s wrong.

2. Reduced engine power

If the DPF is blocked, the exhaust system will be affected dramatically. The ability to efficiently remove the exhaust from the engine is hampered, creating a backup in the system.

With the backup, the engine feels weak and sluggish. As more exhaust builds up, new fuel can be pumped in more slowly, preventing you from accelerating normally. In addition, the engine has to use more power to push out the excess gases.

RELATED: Car Loses Power When Accelerating? (Here are the causes)

3. Poor fuel efficiency

If the engine is not working efficiently, you will burn more fuel than normal. Some of the inefficiency comes from the clogged filter itself, causing more fuel to be pumped in to do the same job. It is also caused by the need for more fuel to get the desired results from your engine.

With these problems, you will end up spending more money on the pump. As the cost of diesel continues to rise, you’re sure to notice the difference.

4. Problems starting

The clogged DPF causes exhaust gas to build up in the engine. This trapped gas has nowhere to escape and creates more pressure than normal. During this time it becomes difficult to crank the engine. In fact, the engine will not start unless this pressure is relieved.

This issue is more of a security design. If the engine were to start with all that pressure inside, permanent damage could result, leading to high repair bills. To save yourself that money, it’s best to clean the DPF before a clog occurs.

RELATED: Car Hesitates to Start – Causes and How to Fix

5. Strange smells

As the exhaust gas builds up in the engine, there can be a noticeable odor nuisance. This is not only annoying, but can also be dangerous.

Exhaust fumes are not safe to breathe and may be flammable, putting you at risk of fire. Additionally, while these smells are present, it’s difficult to tell if something else is wrong.

RELATED: 8 Car Smells And Smells You Shouldn’t Ignore

6. Turbocharger damage

With a clog in the exhaust system, you also need to consider the health of the turbocharger. When gas flow is obstructed or slowed, temperatures can rise rapidly. If the problem is not corrected in a timely manner, the turbine housing will also become hotter.

Without checking, the turbocharger will be damaged. If the casing is damaged, leaks can occur and efficiency drops. This problem can also cause the oil in the turbocharger to carbonize, which becomes dangerous for the engine itself.

Location of the diesel particulate filter

The diesel particulate filter (DPF) is part of the exhaust system of your diesel vehicle. The filter sits in front of the NOx trap, also known as the NOx storage catalytic converter. You can often find the DPF filter near the exhaust manifold.

It is also in front of the exhaust pipe, but behind the first temperature sensor. To remove the filter you will need a screwdriver to remove the surrounding grilles and panels. After the plates are removed, some o-rings or other clamps can also be removed.

Diesel particle filter function

The diesel particulate filter is part of the exhaust system. It is designed to capture particulate matter such as ash and soot. The DPF is constructed with a substrate made of ceramic material. It forms a honeycomb structure that effectively traps dirt.

The diesel particle filter is designed to capture and store the soot from the exhaust gas so that the diesel vehicle can have reduced emissions. This soot is regularly burned to help regenerate the DPF. This regeneration process burns excess soot and deposits it back into the filter, reducing the harmful emissions and black smoke you are used to from diesel models when accelerating.

DPFs have now been mandatory on all vehicles since 2007 under EPA guidelines. These filters capture matter to enable the vehicle to meet strict emissions standards.

Cost of replacing the diesel particulate filter

A brand new diesel particulate filter can cost anywhere from $1,000 to $7,000. These new parts never come cheap, which is why it’s important to get the system working properly. Instead of replacing it, most people choose to purify it for more life.

Considering that the DPF does not usually fail in a low-mileage vehicle, it makes more sense to clean it. After all, the cost of a new DPF could exceed the value of the vehicle itself. With proper maintenance, the DPF should not need to be cleaned more frequently than every 100,000 miles.

How to clean a diesel particulate filter

1. Thermal

If you take the DPF to a professional for cleaning, you may hear it using the thermal method. This cleaning technique is also known as “Bake and Blow”.

The DPF is placed in an oven. The increased heat oxidizes the soot while the airflow pushes the ash out of the filter.

2. Watery

This other professional method has proven to be effective. A surfactant surrounds the ash particles and makes it easier for the water to wash the debris off the substrate.

Once the substrate is cleaned, it needs to be completely dried. It requires a special case, so you’ll have to wait at least two hours before it can be reinstalled.

3. Household cleaners

If you don’t want to take your vehicle to a professional for cleaning, you can try it yourself with a special additive. You can find some top brands for less than $25 a bottle. These products are designed to break down soot and ash.

Follow all directions on the back of the bottle. You must put it in the fuel tank with the engine running. Once it’s added, it’s best to drive for thirty minutes. This supports the circulation of the additive in the system. It doesn’t matter what speed you drive, it will work. Also, the DPF warning light may disappear if it was previously on.

While cleaning additives can clear some clogs, they are best used for maintenance. If you use a cleaner every three to six months, you shouldn’t have clogging problems later.

If you are still having trouble after using an additive, you may need one of the professional cleaning methods instead. Visit your local diesel mechanic for further assistance.

exhaust back pressure of the engine

Hannu Jaaskelainen

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Summary: Exhaust system components such as mufflers and exhaust aftertreatment devices are a source of engine exhaust back pressure. Elevated levels of back pressure can cause increased emissions and fuel economy and adversely affect engine performance.

introduction

definition

Engine exhaust back pressure is defined as the exhaust pressure created by the engine to overcome the hydraulic resistance of the exhaust system in order to discharge the gases to atmosphere. For this discussion, exhaust back pressure is the excess pressure in the exhaust system at the outlet of the exhaust turbine in turbocharged engines, or the pressure at the outlet of the exhaust manifold in naturally aspirated engines. The term back pressure can also be written as one word (back pressure) or with a hyphen (back pressure).

It should be noted that the term “back pressure” is counterintuitive and can obscure a proper understanding of exhaust flow mechanics. The word back seems to imply a pressure applied to a fluid in the opposite direction to its flow—indeed, definitions of this type of back pressure are common in sources of loose scientific standards. There are two reasons to disagree. First, pressure is a scalar quantity, not a vector quantity, and has no direction. Second, gas flow is driven by a pressure gradient, with the only possible direction of flow being from higher to lower pressure. Gas cannot flow against increasing pressure – it is the diesel engine that pumps the gas, compressing it to a pressure high enough to overcome the flow obstacles in the exhaust system.

Given how well established it is among engine designers, we use the term ram pressure as defined above to denote the exhaust pressure at the outlet of the turbo (or exhaust manifold), which is numerically equal to the exhaust pressure drop across the entire exhaust system. However, we believe that the use of this term should not be extended to denote the exhaust pressure drop across specific exhaust system components, as is occasionally used by some authors. For example, we avoid using the term “muffler back pressure” in favor of “muffler pressure drop” (or “head loss”), in accordance with the terminology used in fluid dynamics.

Common metric units of exhaust back pressure are kilopascals (kPa) – which we use in this document – and millibars (mbar), the latter being equivalent to hectopascals (hPa). Common units are inches of water (in H 2 0) and inches of mercury (in Hg). The following relationship exists between these units:

1 kPa = 10 hPa = 10 mbar = 4.0147 in H2 0 = 0.2953 in Hg(1)

back pressure effects

While back pressure has always been a concern of exhaust system designers, interest in exhaust pressure has increased with the equipping of diesel engines with diesel particulate filters (DPF) and the introduction of complex aftertreatment systems in general. The installation of DPFs often raises concerns about increased exhaust back pressure. Under normal circumstances, the pressure drops caused by a muffler and by a properly designed DPF can actually be similar. Figure 1 shows the effect of replacing the OEM muffler with a DPF on a heavy duty diesel engine in two different modes of the ISO 8178 cycle. With a clean filter, the change in back pressure is less than 1 kPa.

Figure 1. Turbine outlet pressure with muffler and clean DPF 1997 Cummins B3.9-C EPA Tier 1 Nonroad engine with muffler and retrofitted with a 6 liter DPF

However, most of the exhaust gas pressure drop across a DPF is caused by the accumulated soot rather than the filter substrate. Problems arise when the regeneration of the DPF does not occur regularly, causing its pressure drop to rise to unacceptable levels.

Increased exhaust gas pressure can have the following effects on the diesel engine:

Increased pumping work

Reduced boost pressure in the intake manifold

Cylinder scavenging and combustion effects

turbocharger problems

At increased levels of back pressure, the engine must compress the exhaust gases to a higher pressure, requiring additional mechanical work and/or less energy extracted from the exhaust turbine, which can affect intake manifold boost pressure. This can lead to an increase in fuel consumption, PM and CO emissions, and exhaust gas temperature. The increased exhaust gas temperature can lead to overheating of the exhaust valves and the turbine. An increase in NOx emissions is also possible due to the increase in engine load.

Other effects on diesel combustion are possible, but depend on the engine type. Increased back pressure can affect turbocharger performance and cause air-fuel ratio changes – usually enrichment – which can be a source of emissions and engine performance problems. The size of the effect depends on the type of charge air systems. Increased exhaust gas pressure can also prevent some exhaust gases from exiting the cylinder (especially on naturally aspirated engines), creating internal exhaust gas recirculation (EGR), which is responsible for some NOx reduction. Slight NOx reductions reported with some DPF systems, typically limited to 2-3% percent, may be explained by this effect.

Turbochargers typically use engine lubricating oil as their lubricating and cooling medium. Excessive exhaust pressures can increase the likelihood of turbocharger seal failure, resulting in oil leakage into the exhaust system. In systems with catalytic DPFs or other catalysts, such an oil leak can also result in catalyst deactivation due to phosphorus and/or other catalyst poisons present in the oil.

back pressure limits

All engines have a maximum allowable engine back pressure specified by the engine manufacturer. Operating the engine with excessive back pressure may void the engine warranty. To facilitate the retrofitting of existing engines with DPFs, particularly using passive filter systems, emission control manufacturers and engine users have requested that engine manufacturers increase the maximum allowable back pressure limits on their engines.

Silencers generally lead to maximum back pressures in the range of 6 kPa. In exhaust systems with DPF, the back pressure can increase to significantly higher values ​​- especially if the filter is heavily loaded with soot. The Swiss VERT program specified maximum back pressure limits to allow the installation of DPFs in a variety of devices [1319] . Table 1 shows VERT’s recommended back pressure limits for a range of engine sizes. Exhaust pressure for large engines was limited to low values ​​due to valve overlap and high boost pressure considerations.

Table 1

VERT maximum recommended exhaust back pressure Engine size Back pressure limit Less than 50 kW 40 kPa 50–500 kW 20 kPa 500 kW and more than 10 kPa

Engine manufacturers tend to be much more conservative about their back pressure limits. For example, Caterpillar, Cummins, John Deere and DDC/MTU diesel genset engines ranging in size from 15 to over 1000 kW have back pressure limits of 6.7 to 10.2 kPa.

There are many factors to consider when setting back pressure limits. These include the influence on turbocharger performance, exhaust emissions, fuel consumption and exhaust gas temperature. The limit that a given motor can tolerate depends on certain design factors and it is difficult to make general recommendations.

###

Jan 08, 2018 – 8:32 am

Hi,

It should be on the high pressure pipe after the turbo up near the back of the engine on the exhaust side. If you’re having trouble finding it, it might be best to take it to a shop and they can show it to your truck for you. Thanks very much!

Engine sensors in a vehicle are built in to provide the correct amount of fuel for all operating conditions. A large number of input sensors are monitored by the engine control unit. Sensor technology has become commonplace in modern vehicles today. Sensors increase people’s safety – both on board and on the road, control vehicle emissions and make vehicles more efficient. In this article we will discuss different types of engine sensors used in modern vehicles. Mass Air Flow (MAF) Sensor The MAF (electrical) sensor is an integral part of the engine system. It is controlled by a computer. It is located in a plastic cover between the engine and the air filter. The purpose of the MAF is to calculate the amount of air inducted by the engine in terms of volume and density. To measure the volume and density of air, the sensor uses either a hot wire or a heated filament. After the measurement, it sends a voltage signal to the computer. This allows the computer to calculate the correct amount of fuel needed to maintain the correct fuel mixture for any operating condition. When there is a fault in the MAF sensor, it can cause rough idling, stalling and poor fuel economy. Throttle Position Sensor (TPS) The Throttle Position Sensor (TPS) is a variable resistor attached or mounted to the throttle body and actuated by movement along with the throttle shaft or spindle. The TPS changes the resistance as the throttle opens and closes and sends a voltage signal to the computer indicating the angle or position of the throttle. Thus, the TPS causes the Electronic Control Unit (ECU) to use the data to measure engine load, adjust fuel timing, adjust acceleration and deceleration when the engine is idling or at full throttle, and then make the changes according to the operation before conditions. The fuel rate is either increased or decreased to achieve this. Coolant Temperature Sensor (CTS) The coolant temperature sensor (CTS) is a temperature dependent variable resistor located on the cylinder head or intake manifold. The CTS is an important sensor and the engine’s operating strategy depends on the signal it sends. It is therefore referred to as the “master” sensor. The CTS measures the internal temperature of the engine coolant. It also senses the temperature changes and sends a voltage signal to the powertrain control module (PCM) to determine if the engine is cold, warm, at normal operating temperature, or overheated. Lambda probe The lambda probe is located on the exhaust manifold. This sensor monitors the amount of unburned oxygen in the exhaust. When the fuel mixture is rich, most of the oxygen is consumed during combustion. This leaves little unburned oxygen in the exhaust. The difference in oxygen levels creates an electrical potential that causes the sensor to generate a voltage signal. This helps the ECU check the quality of the fuel mixture to make changes accordingly. The sensor output is high when the fuel mixture is rich and the sensor output is low when the fuel mixture is lean. Manifold Absolute Pressure (MAP) Sensor MAP is a key sensor because it senses engine load. It is mounted on the intake manifold. It monitors the difference between the air pressure in the intake manifold and outside. This sensor reacts to the vacuum in the intake manifold and generates a corresponding voltage signal. Then it sends the signal to the PCM. The sensor’s input is used to adjust the fuel mixture and ignition timing according to the changes. Engine Speed ​​Sensor (ESS) The ESS is a sensor attached to the crankshaft of the car engine. It is different from the vehicle speed sensor. The ESS is used to monitor the engine speed. In other words, it is used to assess the speed at which the crankshaft is rotating. Voltage Sensor The voltage sensor monitors the vehicle’s system voltage and reports it to the PCM so it can increase the vehicle’s idle speed if the voltage drops. Engine sensors are an important technological innovation. They lead to better performance, better quality and more years of riding experience.

P0470 code definition

P0470 is a code that means the sensor responsible for assessing exhaust gas pressure is not working properly.

What the P0470 code means

This code means that the signal provided by the exhaust pressure sensor does not match ambient barometric pressure or manifold pressure. It is associated with code P0471. The only difference between the two is how long the issue has existed for the vehicle electrical/mechanical issue.

What causes the P0470 code?

There are five main issues that could be behind a P0470 code:

The exhaust back pressure sensor is defective

The exhaust back pressure sensor harness is shorted or fully open

There is a poor electrical connection to the exhaust back pressure sensor circuit

The hose leading from the pressure sensor to the exhaust manifold is clogged

The PCM may have failed (extremely unlikely)

What are the symptoms of the P0470 code?

The Check Engine Light will normally illuminate when this code is present. You will also most likely feel a lack of power from your engine.

Manual regeneration is not possible. Finally, the problem can also develop into a crankless start.

How does a mechanic diagnose the P0470 code?

Given how often a P0470 code is involved, the first thing a mechanic will do when looking to diagnose the underlying issue is to check the exhaust back pressure sensor.

Then they disconnect the pipe connecting the exhaust manifold to the exhaust pressure sensor and try to let air through. If that proves impossible, they can use a wire to unclog the cause of the blockage.

Next, the mechanic will inspect the wiring for signs that it has been compromised. The connections must also be checked in a similar way.

The wiring harness that goes to the exhaust pressure sensor can also be disconnected so the power supply circuit can be tested to make sure it is working properly.

If nothing else seems to be working, the problem is most likely due to the exhaust pressure sensor simply not working properly.

Common mistakes made when diagnosing the P0470 code

The most common problem is that the back pressure sensor simply doesn’t get the attention it deserves when diagnosing the problem. Most of the time, that’s where you’ll find the problem, so start there and double-check everything before proceeding, or you’ll waste a lot of time just going back to the sensor or, worse, completely misdiagnose the problem.

How Serious is the P0470 Code?

The longer the P0470 lasts, the longer you’ll be driving a vehicle that’s not living up to its potential in terms of power and performance. However, keep in mind that the sensor may simply not be working properly, meaning it may just need to be replaced, but everything else is working fine.

What repairs can fix the P0470 code?

As we detailed above, the big one replaces the back pressure sensor. Usually this is enough to make the code disappear.

Otherwise, the sensor and associated circuitry must be tested to ensure the former is not malfunctioning due to the latter.

The power supply to the sensor is also tested to confirm that this is not the reason it is not working properly.

The power supply to the exhaust gas pressure sensor should also be measured.

Usually this is a fairly quick fix if one of the above issues is to blame. Even if the symptoms don’t seem particularly bad, you should still have this diagnosed. If the problem causing the P0470 code isn’t one of the above, something far worse could be in the works.

Need help with a P0470 code?

If your vehicle is currently suffering from a P0470 related issue, Vermin Club is ready to help. You can reach one of our service advisors at 1-800-701-6230 or schedule an appointment online. Certified mobile mechanics are available to meet you at home or in the office to assess and repair your vehicle. We will definitely give you a free quote before we ship them too.

Check the engine light

error codes

P0470

exhaust back pressure of the engine

Hannu Jaaskelainen

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Summary: Exhaust system components such as mufflers and exhaust aftertreatment devices are a source of engine exhaust back pressure. Elevated levels of back pressure can cause increased emissions and fuel economy and adversely affect engine performance.

introduction

definition

Engine exhaust back pressure is defined as the exhaust pressure created by the engine to overcome the hydraulic resistance of the exhaust system in order to discharge the gases to atmosphere. For this discussion, exhaust back pressure is the excess pressure in the exhaust system at the outlet of the exhaust turbine in turbocharged engines, or the pressure at the outlet of the exhaust manifold in naturally aspirated engines. The term back pressure can also be written as one word (back pressure) or with a hyphen (back pressure).

It should be noted that the term “back pressure” is counterintuitive and can obscure a proper understanding of exhaust flow mechanics. The word back seems to imply a pressure applied to a fluid in the opposite direction to its flow—indeed, definitions of this type of back pressure are common in sources of loose scientific standards. There are two reasons to disagree. First, pressure is a scalar quantity, not a vector quantity, and has no direction. Second, gas flow is driven by a pressure gradient, with the only possible direction of flow being from higher to lower pressure. Gas cannot flow against increasing pressure – it is the diesel engine that pumps the gas, compressing it to a pressure high enough to overcome the flow obstacles in the exhaust system.

Given how well established it is among engine designers, we use the term ram pressure as defined above to denote the exhaust pressure at the outlet of the turbo (or exhaust manifold), which is numerically equal to the exhaust pressure drop across the entire exhaust system. However, we believe that the use of this term should not be extended to denote the exhaust pressure drop across specific exhaust system components, as is occasionally used by some authors. For example, we avoid using the term “muffler back pressure” in favor of “muffler pressure drop” (or “head loss”), in accordance with the terminology used in fluid dynamics.

Common metric units of exhaust back pressure are kilopascals (kPa) – which we use in this document – and millibars (mbar), the latter being equivalent to hectopascals (hPa). Common units are inches of water (in H 2 0) and inches of mercury (in Hg). The following relationship exists between these units:

1 kPa = 10 hPa = 10 mbar = 4.0147 in H2 0 = 0.2953 in Hg(1)

back pressure effects

While back pressure has always been a concern of exhaust system designers, interest in exhaust pressure has increased with the equipping of diesel engines with diesel particulate filters (DPF) and the introduction of complex aftertreatment systems in general. The installation of DPFs often raises concerns about increased exhaust back pressure. Under normal circumstances, the pressure drops caused by a muffler and by a properly designed DPF can actually be similar. Figure 1 shows the effect of replacing the OEM muffler with a DPF on a heavy duty diesel engine in two different modes of the ISO 8178 cycle. With a clean filter, the change in back pressure is less than 1 kPa.

Figure 1. Turbine outlet pressure with muffler and clean DPF 1997 Cummins B3.9-C EPA Tier 1 Nonroad engine with muffler and retrofitted with a 6 liter DPF

However, most of the exhaust gas pressure drop across a DPF is caused by the accumulated soot rather than the filter substrate. Problems arise when the regeneration of the DPF does not occur regularly, causing its pressure drop to rise to unacceptable levels.

Increased exhaust gas pressure can have the following effects on the diesel engine:

Increased pumping work

Reduced boost pressure in the intake manifold

Cylinder scavenging and combustion effects

turbocharger problems

At increased levels of back pressure, the engine must compress the exhaust gases to a higher pressure, requiring additional mechanical work and/or less energy extracted from the exhaust turbine, which can affect intake manifold boost pressure. This can lead to an increase in fuel consumption, PM and CO emissions, and exhaust gas temperature. The increased exhaust gas temperature can lead to overheating of the exhaust valves and the turbine. An increase in NOx emissions is also possible due to the increase in engine load.

Other effects on diesel combustion are possible, but depend on the engine type. Increased back pressure can affect turbocharger performance and cause air-fuel ratio changes – usually enrichment – which can be a source of emissions and engine performance problems. The size of the effect depends on the type of charge air systems. Increased exhaust gas pressure can also prevent some exhaust gases from exiting the cylinder (especially on naturally aspirated engines), creating internal exhaust gas recirculation (EGR), which is responsible for some NOx reduction. Slight NOx reductions reported with some DPF systems, typically limited to 2-3% percent, may be explained by this effect.

Turbochargers typically use engine lubricating oil as their lubricating and cooling medium. Excessive exhaust pressures can increase the likelihood of turbocharger seal failure, resulting in oil leakage into the exhaust system. In systems with catalytic DPFs or other catalysts, such an oil leak can also result in catalyst deactivation due to phosphorus and/or other catalyst poisons present in the oil.

back pressure limits

All engines have a maximum allowable engine back pressure specified by the engine manufacturer. Operating the engine with excessive back pressure may void the engine warranty. To facilitate the retrofitting of existing engines with DPFs, particularly using passive filter systems, emission control manufacturers and engine users have requested that engine manufacturers increase the maximum allowable back pressure limits on their engines.

Silencers generally lead to maximum back pressures in the range of 6 kPa. In exhaust systems with DPF, the back pressure can increase to significantly higher values ​​- especially if the filter is heavily loaded with soot. The Swiss VERT program specified maximum back pressure limits to allow the installation of DPFs in a variety of devices [1319] . Table 1 shows VERT’s recommended back pressure limits for a range of engine sizes. Exhaust pressure for large engines was limited to low values ​​due to valve overlap and high boost pressure considerations.

Table 1

VERT maximum recommended exhaust back pressure Engine size Back pressure limit Less than 50 kW 40 kPa 50–500 kW 20 kPa 500 kW and more than 10 kPa

Engine manufacturers tend to be much more conservative about their back pressure limits. For example, Caterpillar, Cummins, John Deere and DDC/MTU diesel genset engines ranging in size from 15 to over 1000 kW have back pressure limits of 6.7 to 10.2 kPa.

There are many factors to consider when setting back pressure limits. These include the influence on turbocharger performance, exhaust emissions, fuel consumption and exhaust gas temperature. The limit that a given motor can tolerate depends on certain design factors and it is difficult to make general recommendations.

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The exhaust gas temperature sensor is a thermistor element mounted in cement to protect against vibration and housed in stainless steel to withstand extreme temperatures of up to 900°C.

Changes in temperature lead to changes in the resistance of the sensor, which are transmitted to the ECU as a voltage.

In a TechAssist bulletin, Lucas explains that these sensors protect key exhaust components from overheating and help control emissions.

They are also used in multiple combustion control processes in diesel and gasoline engines, including selective catalytic reduction (SCR), turbocharging, exhaust gas recirculation, and DPF regeneration.

A faulty sensor reporting incorrect voltages can result in poor fuel efficiency as DPF regeneration takes longer to complete.

DPF regeneration

The DPF regeneration process can affect drivability.

Faulty exhaust gas temperature sensors can result in unnecessary regenerations causing driver inconvenience.

Lucas says some sensors are harder to diagnose than others.

PTC sensor failures are often misdiagnosed as DPF problems because they continue to function after the failure, sending incorrect signals to the ECU that interfere with the DPF regeneration process.

NTC sensors are more likely to trigger the check engine light if they fail.

Extreme heat is often a cause of failure over time.

According to Lucas, a common problem with all wired sensors is that wires can break, especially when subjected to severe twists and turns.

They are also easily damaged when replacing other components in the exhaust system.

For this reason, Lucas recommends replacing the exhaust gas sensors at the same time as the exhaust system or components such as the DPF or KAT.

Exhaust gas temperature sensors have many features that help them withstand vibration, but they can still take their toll over time.

Installation instructions 1. Make sure that the exhaust system has cooled down before you start work. 2. Handle the exhaust gas temperature sensor carefully, dropping the component may cause invisible damage to the cement securing the thermistor. 3. If the sensor has a thread, clean the thread in the exhaust pipe with a cleaning tap. 4. Apply copper grease to the sensor threads only. Although some sensors are pre-greased, additional grease will prevent thread galling and reduce friction, which could result in over-torque (especially with stainless steel threads). Torque wrench to avoid over-tightening and/or damaging the wire. 6. Start the engine and check that the exhaust system is working properly. A reset of the ECU may be necessary.

With just 100 part numbers, Lucas Electrical’s range of exhaust gas temperature sensors covers over ten million vehicles on the road.

To learn more about and view Lucas Electrical’s range of exhaust gas temperature sensors, select “More Details” below.