How do you clean the EGR valve on 1997 Miata?

Answer 1

Ahh, the p0402 check engine light.

First make sure you're using throttle body cleaner, not carburetor cleaner. Carb cleaner will eat away at the lining on the inside of your manifold.


First remove the EGR valve. It's right on the back of your manifold and looks like a metal mushroom. Next unplug the wiring harness and hang it out of the way. The valve itself comes off fairly easy with two 10mm screws although you'll notice a wire brace has to be removed to get the screws out.


Now take the valve itself and go to town with your cleaner and some q-tips. Also, you'll notice that you can take a pencil and push down on the actual valve mechanism through the top hole. Do this as you clean to make sure the cleaner goes all the way through the valve.


Once the valve itself is as spotless as you can get it try your best to clean the insides of the holes on the manifold itself. When you're done replace the valve and the wiring harness and make sure it's bolted on nice and tight. There's no reason to use a gasket on this part. Then replace the wiring harness.


Now disconnect your positive battery terminal for about 20 seconds to turn off the check engine light and go for a drive. If the CEL comes back on then try again, otherwise you're good.