What is the EVP Position Sensor all about?

Vehicle manufacturers have been improving methods of controlling vehicle emissions in their fossil-fuel burning engines since the introduction of the exhaust gas recirculation (EGR) system in 1966. The EGR system brings exhaust gases containing unburned fuel back into the intake manifold where it goes through the combustion process again to cleanly burn the exhaust gases. As the EGR systems advanced, they went from using a vacuum system that controls the flow to an electric valve that opens, closes, and regulates the flow of exhaust gases.

The EGR system employs a valve position (EVP) sensor to detect the position of the gate allowing gases into the intake manifold. This EVP position sensor relays information back to the engine control module, which adjusts the amount of EGR valve flow to run most efficiently. The communication is performed several times per second and the EVP position sensor never ceases to operate while the engine is running. If the EVP position sensor fails, the Check Engine light will come on. The engine may not start or run easily when cold.

Keep in mind:

• Exhaust systems run extremely hot and should not be worked on until they’ve been allowed to completely cool down.
• EVP problems have similar symptoms to many other issues and should be properly diagnosed by one of our expert mechanics.

How it's done:

• The EVP sensor is faulty and needs replacement
• The defective EVP sensor is removed
• The new EVP sensor is installed
• The engine is scanned for codes
• The vehicle is road tested for proper operation and no check engine light comes on.

Our recommendation:

If you suspect you have a faulty EVP position sensor, have one of our expert mechanics perform a diagnostic test on the EGR system. Have the EVP position sensor replaced if necessary.

What common symptoms indicate you may need to replace the EVP Position Sensor?

• Check Engine light is on
• Engine is difficult to start when cold
• Engine runs rough when cold
• Vehicle has failed a smog test

How important is this service?

In addition to failing a smog test, your vehicle’s engine may not start or run well on a cold start, or may run poorly at idle. Have the EVP position sensor replaced as soon as possible.