Skip the auto shop - Our mechanics make house calls

Q: Fixed car after Service Engine Soon light came on. It's still not working right

asked by on

I have replaced almost everything in my car, and it's still not working right. The Service Engine Soon light came on, and I was told it was random misfiring. I replaced plugs, wires, etc., already

A: I can understand how frustrating it can be ...

I can understand how frustrating it can be to replace parts on your car only to have it continue to experience problems. There can be several reasons why your Pontiac has its’ Service Engine Soon Light illuminated. If there is a misfire present after performing a basic tune-up, which includes replacing the spark plugs and ignition wires, then next we need to determine what else could be causing your Pontiac’s problems. I would first start with reading the computer on the vehicle. This is best step towards verifying which codes may be causing the SES light come on. From my experience, it is also possible that your Grand Prix may be having fuel issues, perhaps due to a lack of fuel pressure or a problem with one or more of the fuel injectors. Another common possibility is that the misfire is being caused by internal engine damage, such as a bent valve. With a sensitive issue like this, I find it best to enlist the assistance of a certified mechanic to come out and determine the fixes for your car’s Service Engine Soon Light.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Intake plenum

If the engine runs perfectly fine, this is likely not a spot for a vacuum hose. If a vacuum hose went there, the engine would run very poorly due to the major vacuum leak. I know that the 3.1L V6...

Q: Are the repairs more expensive on this vehicle than on other types of SUVs or trucks?

Hi there: Thanks for writing into YourMechanic.com today seeking advice about buying a reliable SUV. First off, I'd stay away from the Ford and Cadillac Escalade for one simple reason - they both have pretty high ride height; so getting...

Q: Ocassional shifting problems

Hello there, a few different faults could cause the vehicle to shift poorly. The most common would be low transmission fluid level, a shift solenoid, transmission linkage damaged, or a transmission range sensor. Always the first thing checked in any...

Related articles

How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the P0052 code means This code is seen when the Engine Control Module (ECM) tries to control the...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...