What the heck it wrong with our 2002 Pontiac Sunfire?

Asked by Jul 21, 2014 at 09:32 AM about the 2002 Pontiac Sunfire SE Coupe

Question type: Maintenance & Repair

Our 2002 Pontiac Sunfire died on the highway. Husband started it back up and drove
another couple miles before it died again. This time it would turn over but not start. Towed
it home and mechanic hooked the code reader up to it. Says needs fuel pump. Replaced
the fuel pump and still won't run well. All of a sudden, misfire on two cylinders! This car
ran perfectly before the fuel pump went out!  So code reader again. Getting a P0300 and
a U-1040 code. Changed plugs and still no power. Husband is ready to get rid of it! I'm
not so sure it's that serious. Can anyone help with this? It's the 2.4 liter.

2 Answers

4,575

It might be as simple as a load of bad gas, but I bet the entire problem is the U-1040 code. This basically means that the ECM is not communicating with one or more of the various sensors properly, and this will shut the engine down, along with a host of other issues. The fuel pump was probably okay, injectors and plugs were probably okay. The other OBD trouble codes pop up because the ECM isn't getting the data back that it expects. Clean all the connectors in the ECM harness, check all the fuses and relays, get the U-1040 code cleared from the system and then check the OBD again in 24 hours.

2 of 2 people found this helpful.

Thanks Norm. We will start trying all of this. Is there a way we can check which of the sensors is the specific problem? The code U-1040 just says "module mis-communication".

1 of 1 people found this helpful.

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