EGR Valve Issues - Hard to Diagnose, Easy to Fix

In vehicles made in the past twenty or so years, exhaust gas recirculation (EGR) valves are basically standard equipment. They are used to send some of the exhaust from the engine back into the cylinders for re-burning to improve tailpipe emissions. To find out more about EGR valves, read our article about them here.

Recently in our Ask a Mechanic forums, Bridget asked about the EGR valve engine error code on her Chrysler Town & Country minivan. The engine light came on to tell her something was wrong and she took it to the dealership where she was told it was the EGR valve. They reset the computer to turn off the light, but it came right back on, of course. The problem hadn't been fixed, just the most general of diagnosis had been given.

When the EGR Isn't the EGR

Sometimes, an EGR code will be thrown by the computer even if nothing is wrong with the EGR valve itself. Sensors around the valve, including oxygen sensors and intake sensors, can trigger EGR codes instead. This is why it pays to only use the computer as a general guideline towards focusing your diagnosis. If the engine is running roughly or you aren't passing emissions testing, then the computer may be able to tell you to look at the EGR, but that's not always the problem, it's just a first place to look.

Symptoms that Might Point to the EGR

If your engine's computer isn't registering anything, but you're having problems, there are ways to decide whether the EGR has anything to do with them.

A common problem caused by a clogged or stuck EGR valve is engine choking or cutoff at idle. This can happen if the valve is stuck open or won't close all the way, allowing exhaust gases to enter the airflow and disrupt the fuel burning by lowering oxygen totals in the cylinders. If the car chokes out (dies) but then starts right back up without problems, this is the likely cause.

Big fuel economy losses, especially relatively sudden ones, can also mean an EGR problem. If the valve is stuck closed (does not open) or will not open past a certain point, it can mean less reburn and thus lower fuel economy.

When the Valve is Stuck

Whether open or closed, a stuck valve doesn't necessarily mean replacing. Depending on the vehicle, many EGR valves can be removed and cleaned to restore them. This is an easy, quick fix most DIY mechanics can do themselves. If it doesn't work, you can replace the valve, of course, but if it does work, it saves you a trip to the auto parts store and the cost of the new valve.

If it does require replacement, the EGR on most vehicles is under $100.