How to Determine if the EGR Valve of a B12 Engine is Faulty?

[EmmanuelLee]

EGR valve malfunctions can be categorized into being stuck or inoperative. Below are the detailed descriptions: 1. Stuck: When stuck, it can cause unstable engine idle, severe shaking, or even stalling. This is because the EGR valve should be closed during idle. If it opens, it allows exhaust gases to enter the intake system, leading to insufficient air intake and, consequently, insufficient power, which results in engine shaking or stalling. Most cases of being stuck are caused by carbon buildup. 2. Inoperative: When inoperative, it does not affect the engine's power output; in fact, it might even increase the engine's horsepower. This is because when it is inoperative, it does not open, so the exhaust gases that would normally enter the cylinders to reduce air intake (lowering combustion chamber temperature) are not present. As a result, more air enters, increasing horsepower. However, this can lead to poor exhaust emission when the combustion chamber temperature is too high. Therefore, if the vehicle has this issue, it should be repaired as soon as possible. Inoperative conditions may be caused by carbon buildup, a faulty EGR solenoid valve, or issues with the circuit that drives the solenoid valve from the engine control unit.