To curtail emissions, manufacturers have placed an exhaust gas recirculation system (EGR) on most vehicles regardless of whether they are petrol or diesel propelled.
The EGR system pulls nitrogen oxides from the exhaust and recirculates them back into the system. Nitrogen oxides are a byproduct of the ignition of the fuel within the combustion chamber. NOx emissions are pollutants that the EGR system pulls out, so your exhaust is cleaner. The system is sensor-driven, and the valve controls the flow of exhaust.
The valve is normally closed when the vehicle is not running and stays open while driving, so it can continuously monitor and adjust to driving conditions.
The EGR valve is subject to extreme heat and use, so it can become clogged with carbon deposits.
Here are some symptoms of a clogged EGR valve:
Check Engine Light is Lit – This is a common warning that appears whenever there is a problem within the engine system, including the emissions and exhaust systems.
Excessive Smoke – One of the benefits of the EGR system is that it recirculates the exhaust fumes. If the valve is stuck, those exhaust fumes are going to go out of the tailpipe.
Running too Lean – There will be a drop in fuel efficiency if the EGR valve is not operating. Since it monitors the fuel-to-air ratio, a bad reading can send too little fuel for combustion.
Poor Acceleration – Because the ERG system monitors fuel efficiency, a stuck EGR valve will cause acceleration issues. If the valve is stuck open, you will notice problems at lower speeds, and higher speed issues if the valve is stuck closed. Either way, your engine will not perform effectively.
Idle -If you find that there is a rough idle after your engine has warmed up, your EGR valve may be stuck closed. If the rough idle is before the engine warms up, your EGR valve could be stuck in the open position.
Pings – The EGR system takes the pings out of your engine by ensuring that the fuel does not ignite before it should by lowering the temperatures in the combustion chamber. If the valve is stuck closed, you may hear the engine knock.
If you notice any of these symptoms, then check with a professional technician. They have professional diagnostic tools that can read engine codes and troubleshoot the problem for you.