EGR Valve Position Sensor (EVP Sensor)

The EGR Valve Position Sensor is responsible for identifying the exact position of the EGR (Exhaust Gas Recirculation System) valve. This valve measures and controls the number of gases that are expelled into the combustion chamber together with the fuel mixture. Thanks to the regulation established by the EVP Sensor, the emission of Nitrogen Oxides (NOx) is reduced, in addition to eliminating the engine's chattering.

What is the EGR Valve Position Sensor?

This part is a control or monitoring point for the EGR valve or exhaust gas adjustment. Practically, the EVP sensor is found in all vehicles, but especially in diesel injection vehicles. It is considered a part of the anti-pollution system, so it is one of the points to be evaluated in the revisions. This sensor itself is a linear action potentiometer. Where you will find 3 pins, ground, positive, and signal.

What is the EGR Position Sensor used for?

Sensor EVP

The EGR Valve Position Sensor monitors the position of the valve through which the exhaust gases flow. It does this by sensing the position of the EGR valve after the vehicle's ECU has sent the signal.

How does the EVP Sensor work?

It is a continuous process or cycle where the EVP Sensor checks the position of the EGR valve and sends signals to the ECU to determine the operation based on the temperature, speed, and load of the gases and the engine. The process occurs consecutive times per second.

Changes in the EGR valve opening generate an electrical resistance that the EVP sensor registers. This voltage signal will increase as the valve opens, indicating that it will have greater resistance as it closes.

Mechanically, the sensor is positioned on the valve, and the sensor has a shaft. This shaft is pressed by the valve as the valve opens. In this instance, the gas recirculation flow is managed by the ECU.

EVP Sensor Failures

It is a sensor that tends to suffer wear since its operation is very constant. The failures of this sensor affect the operation of the EGR valve and can cause engine failures.

Symptoms of EGR sensor or valve failure

In addition, there may be other symptoms associated with this failure:

  • Heavy black smoke from the exhaust.
  • Pulling on start-up.
  • Catalytic converter overheating.
  • Unstable idle.

EVP sensor interference in the EGR valve

Nowadays, the emission control of vehicles is measured and checked annually. So, these two components, the EVP Sensor and the EGR valve work synchronized. This function between the two allows the combustion gases to pass back into the system and burn at a higher temperature, allowing less harmful gases to be released into the environment. In turn, it allows the same circulating gases to serve as an additional engine performance enhancement.

The fault codes that can be generated by problems in the EVP Sensor are as follows:

  • P0405: Input or output voltage low.
  • P0401: Insufficient gas circulation.
  • 31-32: EGR valve control error.

In the event of a fault code for a sensor failure, the Check Engine Light on the dashboard will illuminate.

How to test the EVP Sensor?

To check the well-being of the sensor you must have a multimeter and do the following:

  • Identify each terminal of the sensor. Keep in mind that there is a ground, a positive or voltage, and an output signal pin.
  • Select the volts option on the multimeter.
  • Place the tip of the multimeter lead on the output pin and start pulsing or depressing the sensor tip. Each time you do this you should get a reading on the multimeter.
  • Check these values in the manufacturer's technical bulletins to confirm that they are correct.

How to maintain the EVP Sensor?

There is really little that can be done in terms of maintenance or cleaning the EGR Position Sensor. Rather, it is to check conditions. Such as, for example, that the wires are not corroded, that the connector is not fractured or sulfated, and that the hoses that communicate the intake with the exhaust are clean.

Where is the EVP sensor located?

In most cases it is located between the intake and exhaust, coupled to the EGR valve will be the EVP Sensor. You can find out the exact location of the EVP Sensor by acquiring the car's electrical diagrams.


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