Symptoms of a Bad or Failing EVP Position Sensor

position sensor

The EVP sensor is an emission system component found on certain vehicles. It is a part of the EGR system, the emissions system that recirculates exhaust gases back into the engine to reduce cylinder temperature and NOx emissions. The EVP sensor monitors the position of the EGR valve so that the computer can adjust it according to operating conditions. [When the sensor fails] it can cause problems with the functionality of the EGR system, which can result in increased emissions. Usually a bad or failing EVP position sensor will produce a few symptoms that can alert the driver of a potential problem that should be serviced.

1. Poor cold start performance

One of the first symptoms of a potential problem with the EVP sensor is poor cold start performance. If the EVP sensor fails it can send an incorrect signal to the computer, which will affect the flow of the EGR system. Improper EGR flow may cause engine performance issues, such as difficulty starting, rough idle, and even misfires, which may be most prominent at cold starts.

2. Check Engine Light comes on

Another symptom of a potential problem with the EVP position sensor is a Check Engine Light. If the computer detects an issue with the EVP position sensor or circuit it will set off the Check Engine Light to alert the driver of a potential issue. The Check Engine Light can also be set off by a wide variety of other problems, so having the vehicle scanned for trouble codes is highly recommended.

3. Failed emissions test

A bad or failing EVP sensor can also result in a [failed emissions test]. If the EVP positions sensor malfunctions and affects the functionality of the EGR system this may result in an increase of NOx emissions. For states with strict emissions requirements, the vehicle may not be able to be registered until the issue is fixed.

The EVP position sensor is an emissions component, and any problems with it can result in the vehicle failing an emissions test. For this reason, if you suspect that your EVP sensor may be having an issue, have the vehicle inspected by a professional technician, such as one from YourMechanic, to determine if the issue should be replaced.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

More related articles

How to Find the Keyless Code on a Ford Explorer or Mercury Mountaineer
Many Ford Explorers and Mercury Mountaineers were manufactured with an option known as the Ford keyless entry keypad. Some models refer to it as SecuriCode as well. It...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the P0052 code means This code is seen when the Engine Control Module (ECM) tries to control the...
P0222 OBD-II Trouble Code: Throttle/Pedal Position Switch/Sensor B Circuit Low Input
P0222 code definition Throttle/Pedal Position Switch/Sensor B Circuit Low Input What the P0222 code means The manufacturer specifies a range of acceptable voltage to be produced from the throttle position...

Related questions

Q: Need to pass smog check

Hi there. Your smog check is measured as to how efficiently your vehicle is burning fuel and air. Smog is reliant on many different components. Your EGR valve, vacuum, and also your catalytic converter are factored potential factors. I would...

Q: car crank not start, 2004 BMW 745i

The code you listed, P1727 indicates that the engine speed sensor is not providing a signal to the computer. Without knowing the position of the crankshaft, the ECM does not know when to inject fuel or when to ignite a...

Q: ABS signal and Check Engine signal

Hello there. I would need a better description of any symptoms your car is experiencing for more precise advice. There are at least eight sensors on the engine. The camshaft or crankshaft sensor are a couple of the most common...