What to know about the EVP Position Sensor:
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 thoroughly 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 controls the flow of exhaust gases.
The EGR system brings a valve position (EVP) sensor to detect the position of the gate enabling 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 done several times per second and the EVP position sensor never ceases to work while the engine is operating.
If the EVP position sensor malfunctions, the Check Engine light will come on. The engine may not start or run easily when cold.
Facts to Note:
Exhaust systems run extremely hot and should not be worked on until they’ve been allowed to completely cool down.
EVP problems have similar signs to many other problems and should be properly analyzed by one of your expert mechanics.
How to Fix:
The EVP sensor is defective and needs replacement
The faulty EVP sensor is removed
The new EVP sensor is fixed
The engine is scanned for codes
The vehicle is road tested for correct operation and no check engine light comes on.
If you suspect you have a defective EVP position sensor, have one of your expert mechanics do a diagnostic test on the EGR system. Have the EVP position sensor changedif necessary.
Common symptoms indicating you may need to change 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
Importance of 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 changed as soon as you can.