What are the symptoms of a faulty EGR valve in a B12 engine?
2 Answers
The most obvious symptom of a faulty EGR valve is that it causes the engine's idle to become extremely unstable, or even stall. The EGR valve is a component of the exhaust gas recirculation control system. When the EGR valve is faulty, symptoms may include extremely unstable idle or stalling, flashing check engine light, failure to meet emission standards during annual inspection, burning oil, and blue smoke from the exhaust. Below is additional information: 1. EGR Valve: The EGR valve is an electromechanical product installed on diesel engines to control the amount of exhaust gas recirculated back into the intake system. It is usually located on the right side of the intake manifold, near the throttle body, and is connected to the exhaust manifold via a short metal pipe. 2. Function: Its role is to control the amount of exhaust gas entering the intake manifold, allowing a certain amount of exhaust gas to flow into the intake manifold for recirculation. The EGR valve is a very important and critical component in the exhaust gas recirculation system, used to reduce the emission of nitrogen oxides (NOx) in the exhaust.
I've been repairing cars for over a decade, and if the EGR valve on a B12 engine fails, it causes a bunch of problems. The most common issues are unstable idling—the car shakes when starting up and the engine vibrates heavily while driving. Power also drops; stepping on the accelerator feels weak, as if the engine's strength has been drained. Fuel consumption definitely increases—what used to be 10 liters per 100 kilometers can jump to 12 liters, burning more money over time. The exhaust warning light will come on, indicating excessive emissions, which happens when the valve malfunctions and disrupts the exhaust gas recirculation system. If left unrepaired for too long, it may lead to engine overheating and damage critical components like the catalytic converter, making repairs even more expensive. I recommend using a diagnostic tool to check the trouble codes, then disassembling and cleaning the valve—dirt buildup can cause it to stick. If it's completely broken, replace it with a new one immediately. Don’t let a minor issue turn into major damage.
