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What is the Purpose of the EGR Valve?

Model: (Various brands) Various
Part: EGR valve

The EGR valve is used to reduce nitrogen oxides (NOx): as mentioned in the video, it draws exhaust gases from the exhaust system and brings them back into the intake. The exhaust gases, once reintroduced into the intake, have little oxygen, dilute the air-fuel mixture, lower the combustion temperature, and with lower temperatures, less NOx is formed. The EGR valve is subject to carbon build-up. If the valve gets stuck closed, the vehicle does not reduce NOx; if it gets stuck open, the car continuously consumes exhaust gases, leading to ignition problems, rough idling, the vehicle not starting, or going into limp mode. It is possible to clean it with specific spray if it is just caked. If the actuator (the electrical or mechanical part that moves) is stuck, it needs to be replaced. Physically removing the EGR is illegal for road use: removing it via the ECU is a modification that makes the car non-compliant and exposes us to hefty fines and failure to pass the MOT.

Posted on 21 May 2026 by ScegliAuto

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