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Questions and Answers

Pontiac Sunfire Check Engine Light On

Q. My husband and I have a 1997 Pontiac Sunfire. A few weeks ago the Check Engine Light (CEL) came on and stayed on. We took it to the dealership and they did a diagnostic test on the car. It came up with a code P0300. They told us that this meant that the #3 Fuel Injector was misfiring and that it needed to be replaced.

Pontiac Sunfire Check Engine Light On

My husband being a retired auto mechanic replaced the #3 Fuel Injector. He cleared the code and after 22 miles the CEL came back on again. So this time we took it to an Auto Parts Store and they did a Diagnostic test on the car. It came up with a code P0401. They told us that this meant that there is Insufficient EGR Flow.

My husband checked the vacuum on the EGR valve and it has good vacuum and he cleaned out the EGR Valve by using carbon cleaner. He even cleaned out all the manifolds. He cleared the codes and after 22 miles the CEL came on and the code was the same.

My husband thought that the EGR valve went bad, so we bought a new EGR Valve. We cleared the codes and after 22 miles the CEL came back on with the same code. My husband wants to know if the PCM could be bad or if we bought a bad EGR Valve?

He's not sure on what to do at this point. We took it to the dealership and they really don't know what's wrong with the car because there is no code coming up on the diagnostic test.

Thanks!
Trina
Noblesville, IN

A. It sounds like your husband is on top of this! Maybe if he went to the dealer and asked for a printout of a copy for the P0401 diagnostic chart he could get a better explanation of what the PCM is doing and looking for when this code sets.

I can't figure why the dealer gets no code and someone else does. Once the light comes on a snapshot is taken and stored in the memory for a tech to look at. Only most dealers have the proper scanner to view these snapshots.

My guess is the code is wrong. Maybe it's a P0440? Anyway, make sure this code is read properly before throwing any more money at it.

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