5 SYMPTOMS OF A BAD EGR VALVE
purpose
The purpose of the EGR valve (exhaust gas recirculation) is to open up and recirculate part of the exhaust gases back into the intake manifold. These exhaust gases help reduce the temperature of combustion. This is very important because NOx is formed in high temperatures, so reducing the temperature reduces the NOx formation.
When it comes to symptoms of a bad EGR valve it can go in 2 different directions. You can have symptoms of a stuck-open EGR valve or you can have symptoms of a stuck-closed EGR valve.
symptoms
engine light
The first symptom of a bad EGR valve is an engine light. Here are some codes that may show up:
P0400
P0401
P0402
P0403
P0404
P0405
P0406
P0407
P0408
P0409
Ensure you can access your car's diagnostic codes by acquiring an OBD2 scanner here.
failed emissions
The second symptom of a bad EGR valve is your vehicle failing the emissions test. This can be due to a stuck-closed EGR valve. A stuck-closed EGR valve will prevent exhaust gases from coming into the combustion process. If the exhaust gases don’t come in, the temperature inside the chamber will increase and produce more NOx. Too much NOx will lead to your car failing the emissions test.
engine knock
The third symptom of a faulty EGR valve is hearing an engine knocking sound. This happens when an unplanned mini-detonation occurs during the power stroke in combustion. People describe it as a pinging noise. A stuck-closed EGR prevents exhaust gases from coming inside the combustion to cool it down for proper temperature levels. Hot temperature levels inside the combustion can ignite air and fuel at unwanted times which creates the engine knocking sound.
bad acceleration
The fourth symptom of a bad EGR valve is acceleration issues. A stuck-open EGR valve can be the cause of this symptom. A stuck-open EGR will continuously add exhaust gases back into the combustion chamber. These gases will take up space, therefore, limiting the amount of air that enters for optimal engine performance. This is why your acceleration is lacking.
rough idle
The fifth symptom of a stuck open EGR valve is a rough idle. The same reason occurs here. Since the EGR is stuck open, the exhaust gasses take up space inside the combustion process, not leaving much room for air to combust with fuel efficiency. This leads to improper combustion which results in your car having vibrations.
If you figured out the EGR valve in your car is faulty, try using this cleaning chemical to clean it first, before buying a new EGR valve.
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