The EGR system is the most vital part of the vehicle that controls the emission of NOx. The ENGR system consists of an EGR valve, EGR cooler, and EGR sensor. The main function of the EGR sensor is to control the flow of exhaust gases through passages and the position of the EGR valve pintle. This article mainly explains the different aspects of the EGR sensor.
What is an EGR Sensor?
The EGR position sensor senses the motion and position of the EGR pintle. The EGR pressure sensor measures the flow of exhaust gases through the EGR passages.
With the help of the EGR sensor, the PCM (powertrain control module) monitors the EGR pressure and uses this information to adjust the pressure. If there is a change during the pressure monitoring process, the sensor reports a new pressure value for validation.
How does the EGR Pressure Sensor work?
The EGR pressure sensor uses exhaust gas pressure from the EGR system to observe the pressure being applied to the EGR system at the desired time. This helps engine control system software designers and manufacturers understand how to adjust the vehicle’s EGR system to adapt to varying pressure conditions.
In case of higher engine speed and load, the EGR pressure sensors observe higher pressure. However, the pressure sensor observes lower exhaust gas pressure at lower engine speed and load.
The ECU takes information from the EGR sensors to increase or decrease the pressure in the EGR system for the efficient working of the EGR system. This process is done by gradually opening and closing the EGR valve until the control unit is fully satisfied with the EGR system pressure.
If the EGR system discharges very high or very low exhaust gases, the sensor can help the engine control unit identify the problem and prevent the system from damage.
Symptoms of a bad EGR Sensor
As the EGR sensor goes bad, it generates the following symptoms:
- Rough Idling
- Poor Engine Performance
- Higher Fuel Consumption
- Fuel Smell
- Higher Emission
1) Rough Idling
Rough idling occurs when the vehicle is started or briefly stopped (i.e. when the engine is warming up at low speed). This rough idling occurs when the EGR is continuously opening, and exhaust gas starts to flow into the intake manifold.
2) Poor Engine Performance
A reduction in the engine performance is a sign of a bad EGR sensor. Improper operation of the EGR valve can cause instability in vehicle performance.
3) Higher Fuel Consumption
If the EGR valve remains open, it increases fuel consumption. The engine may consume a high amount of fuel due to many other reasons, such as a blown head gasket and engine overheating.
4) Fuel Smell
If the car notices a problem with the EGR valve, the check engine light may remain on. This can happen when EGR is continuously on or off.
However, be aware that in many cases, the EGR valve will begin to deteriorate before it fails completely and may not be detected by the PCM. Therefore, you must pay attention to the other symptoms mentioned.
5) Higher Emission
The higher emission of the exhaust gas is a sign of the bad EGR sensor. Sometimes, the emission rate increases due to improper working of the EGR valve.
If the EGR valve is left open, it reduces the temperature and prevents the complete burning of the fuel. This means that the flow of unburned hydrocarbon gas from the exhaust pipe will increase.
If the valve is always closed, high temperatures in the combustor can create extreme NOx gas.
Read More: Causes of Engine Overheating
How to replace the EGR Pressure Sensor?
The proper maintenance and replacement of the EGR valve are very important for the efficient working of the EGR system.
Follow the below-given steps to replace the valve:
- First of all, remove the two rubber or composite rubber hoses from the sensor.
- Remove the metal lines from the exhaust manifold or EGR pipe.
- Now, disconnect the sensor from the electronic connector
- Replace the hose if necessary and install a new sensor.
- Few sensors may use clips or fasteners to attach the sensor. This is as simple as removing the mounting hardware and replacing it with a new sensor.
FAQ Section
Can I drive with a bad EGR Pressure Sensor?
Yes, you can drive with a bad EGR sensor but it is not recommended. Whenever the check engine light is on, especially when it is flashing, you should contact a professional to inspect your car. Don’t ignore the illuminating check engine lights, especially if the problem belongs to the EGR system. A faulty EGR system not only causes poor fuel economy and the above-given signs, but it may also make the vehicle unable to start and drive.
How much does an EGR sensor cost?
The replacement cost of an EGR sensor varies according to the area where you live, vehicle model, and the type of brand. The average replacement cost of the EGR position sensor is from $100 to $150. If you hire labor for this job, the labor cost is from $50 to $75, while the new parts price is from $50 and $80.
What happens when the EGR sensor goes bad?
As the EGR sensors go bad, they generate different issues such as a reduction in engine performance, increased exhaust gas emission, and reduced fuel economy.
What are the signs of bad EGR Pressure Sensor?
- Fuel smell
- Rough idling
- Failed emission test
- Poor engine performance
- Higher fuel consumption