Your vehicle has many parts that work together to keep your car running. Some of them are quite obvious when something is wrong, while others can be difficult to troubleshoot. This is especially true when it comes to the valves under the hood. The exhaust gas recirculation valve (EGR) has the job of recirculating part of the exhaust gas back into the intake manifold. This helps reduce the temperature of the engine during the combustion process. Here is what you need to know about how to tell if something is wrong with this part. 

The Check Engine Light

The most obvious sign that something is wrong with the EGR valve is when the check engine light turns on. You can have a local mechanic read this code and identify the part that is wrong, or you can take your vehicle to a local auto parts store. For example, error code P0400 will tell you that the ERG valve is malfunctioning, while codes like P0409 will narrow down the problem to specific circuits of the ERG valve. 

The Vehicle Fails An Emissions Test

If you recently took your vehicle to get an emissions test, a closed ERG valve can cause your vehicle to fail the test. This is because the exhaust is unable to leave the engine, which causes it to get hotter than normal. Your vehicle will produce more harmful gasses than necessary and you'll have to get your vehicle fixed before it is allowed to be on the road. 

The Engine Knocks

Your engine can also make a knocking sound when the ERG valve is stuck in the closed position. Knocking happens when the combustion process happens at an unplanned time as the piston is moving. Since exhaust gasses can't escape, the air and fuel can combust at an unwanted time and cause that knocking sound. Some people describe the sound as more like a pinging sound, so watch out for that too.

The Car Accelerates Poorly

If the ERG is stuck in an open position, the exhaust gas will flow back into the combustion chamber and take up space that would normally be taken up by air. This creates a bad air-to-fuel ratio, which causes your vehicle to accelerate inefficiently. That same problem can also lead to the car idling roughly, which leads to your vehicle vibrating.

Reach out to an auto repair mechanic if you have something wrong with your EGR valve.