What are the symptoms of a faulty EGR valve in diesel vehicles?
2 Answers
Diesel vehicle EGR valve failure symptoms are as follows: extremely unstable idle speed or even stalling, malfunction indicator light flashing, failing emission standards during annual inspection, burning engine oil, and blue exhaust smoke. When the EGR valve remains constantly open, the vehicle may exhibit black smoke emission, weak acceleration, and increased fuel consumption. The working principle of the EGR valve is as follows: 1. The EGR valve stem rises, pushing the connected sliding contact arm to change position, causing the sliding contact to move along the sliding resistor, generating varying voltage signals. 2. The generated signals are transmitted to the engine control ECU. The engine control ECU monitors the EGR valve position through these signals, ensuring the valve responds correctly to ECU commands. This allows adjustment and correction of the EGR valve opening timing and duty cycle, precisely controlling the recirculation volume to reduce emissions and improve performance.
Last time I was driving, I encountered a faulty EGR valve, and the symptoms were quite obvious. The car felt extremely sluggish, accelerating as slowly as a snail climbing a hill, with no power even when the throttle was floored. Fuel consumption also skyrocketed—normally a full tank would last a week, but now it was gone in just three days, putting a strain on my wallet. At idle, the engine shook violently, making it feel like sitting in a massage chair, and sometimes it even emitted black smoke, creating a dark haze visible in the rearview mirror—not only polluting the environment but also embarrassing. Starting the car became difficult too, with several failed attempts, delaying my commute. Later, during a checkup, it turned out the EGR valve was stuck, completely clogged with carbon deposits, blocking the exhaust gas recirculation system. Such issues must be addressed early, or they’ll damage the engine and cost more money. I promptly replaced the valve, and the car ran much smoother afterward.
