The exhaust gas recirculation valve, or the EGR valve is a small component in your vehicle designed to allow the flow of exhaust gases into the intake manifold in small amounts. This is a simple valve that opens and closes when it needs to. This is either to let exhaust gases into the combustion chamber, or to close in order to prevent the gases from entering. Now, when the car engine comes on, the valve is turned on too, and it stays in a closed position. Once the engine crosses a certain temperature threshold, the EGR valve opens and lets the exhaust gases combine with the air-fuel mixture in the combustion chamber. When the engine is turned off, the EGR valve closes too.
Now, an EGR valve can fail in two ways. It could either fail to open, or it could fail to close. Here are the symptoms of a faulty EGR valve according to the manner of failure:
IF THE EGR VALVE FAILS TO CLOSE
This will let in exhaust gases to the intake manifold continuously. The effects include the following:
- Increase in fuel consumption.
- There will be an odor of fuel in the air while operating the vehicle. This is due to the increase in hydrocarbons leaving the vehicle.
- When the engine dies, there could be stalling.
- The engine could be idling roughly when you start it, or when you are at low engine speeds.
IF THE EGR VALVE FAILS TO OPEN
This blocks the exhaust gases from reaching the intake manifold. Here are some effects of this symptom:
- After the normal ignition, there could be a second ignition, and both could combine to cause serious damage to the engine.
- There could also be tapping or pinging sounds coming from the engine at low revs-per-minute (RPM). This is the sound of early ignition of the fuel when it meets higher temperatures.
Note that in both cases, your Check Engine light will be on. In any case, the above symptoms may not necessarily be due to a faulty EGR valve. But it does not hurt to be sure. If you notice such symptoms in your car, it is best to take it to the mechanic to be checked out and repaired if necessary.