Will clogged EGR valve burn exhaust valves?

95 corolla 250K miles. CEL light on for 7 years or so at 150K miles. Dealer said clogged EGR valve.

I didn’t get it fixed as car was already old at the time.

Is it worth fixing now? Or has the damage already been done or not done?

The car almost never pings, mostly highway driven.

Mechanic said even if you just replace the valve (which costs hundreds) it could still necessitate cleaning passages and such and could cost more.

I wondered if it is just possible to “clean not replace” but he said there’s no guarantee it can just be cleaned and even so, cleaning alone can cost hundreds if it’s all gunked up.

What do you think?

Also rest of car is in pretty good shape (transmission and body anyway).

I don’t know where your EGR valve is located, but on my car it is easily accessible with only two bolts to remove it. Cleaning was very easy for me as well with some throttle body cleaner spray and a pipe cleaner.

A brand new EGR valve costs about $300.00 for your car, so I don’t know what he was saying about cleaning costing “hundreds”.

The pinging can crack pistons. If you can avoid the pinging you can likely avoid any internal damage. You might try a higher octane fuel. But then you might remove the EGR and push a pipe cleaner through the ports to see if that allows the EGR to breath.

The purpose of the EGR is to recycle some of the exhaust gasses back into the intake stream to act as a buffer during the combustion process. This lowers the peak combustion temperature enough to restrict the formation of nitrous oxides which are a pollutant.

Engines used to run at these very high peak combustion temperatures before the engines required pollution controls, but back then, valve seldom lasted much more than 100k miles. Today, valves go far longer than 100k miles, partly due to EGR, partly due to unleaded gas, partly due to better materials, and mostly due to better efficiency of the combustion process.

On most cars, the EGR is fairly easy to clean out.

If egr ports are clogged, a good or bad egr will function the same. It will have no affect.

how expensive is it to clean the egr ports and where are they located? I guess not on the EGR valve itself.

When you remove the EGR valve, there will be two ports, one to the intake manifold, the other goes to a tube that goes to the exhaust manifold. You just spray a solvent like a carburetor cleaner down into these ports.

The one most likely clogged will be the one to the exhaust manifold. If you get spray back from the carb cleaner, stop and fill the tube with SeaFoam or PB Blaster and let it sit overnight, then spray out the next day.

The EGR may not be clogged up completely. When you look at the valve, you will see the corresponding holes, one of which actually has the valve that opens and closes. chances are that there is some buildup on the valve that keeps it from completely closing. Thats not the best description, the valve actually closes, but because of the gunk build up, it doesn’t move far enough to close the switch that tells the computer that it is closed. The switch is the only way that the computer knows that the valve is closed.

With these two holes pointed up, I fill the EGR valve body with SeaFoam and let it sit over night. Then the next day, I spray out with carb cleaner. I also push down on the valve and clean the lip of the opening with a cloth or paper towel so that the valve has full travel when closing, thus making the switch. If you valve opens by pushing outward instead of inward, then this will be a little trickier.