Pontiac Repair: 2004 Grand Am GT Coupe (2 Door)

Question
QUESTION: Hello!

I have a 2004 Grand Am GT Coupe.  The sticker on the door says it was manufactured 03/04.  A few months ago the check engine light went on.  My mechanic diagnosed my car as having a bad "canister vent valve".  I know along with the code that he pulled, he also ran a smoke test.

Since that time, he has replaced this same part 4 times.  Each time it went bad sometime within a few days - 1 month later.  The first 3 times he used GM OEM parts.  This last time he decided to try an aftermarket part.  All have failed.

It is hard for me to believe that all 4 of these parts are manufacturing defects (especially since we've tried both OEM and aftermarket replacements).  Is it possible that another part in the system could be bad therefore causing this part to go bad?

I took a picture of the part # that was on the replacement part bag.  It is GM #1514-2482, ACD #214-2117.

Please let me know if you have any ideas as to what is really going on here.  I'd really appreciate your help!!!

Thanks!
Lori

ANSWER: Hi Lori:

What code(S) are setting with this? somewhere someone is missing the bost on what the root cause here is. It depends on the code. Evap leaks are very hard to find even with a "smoke test" if it's setting a 442 code extrembly hard to find if you don't have the specialzed tools. a 449 code is an eletrical fault and pretty easy to fix. A 455 not that hard to fix either. the small leak is an issue. If you live in the rust belt Like I see MI there is the rust rot factor involved. I have see line rot out on these up by the firewall. I have seen fule filler next rot out and even seen the ice/freeze factor cause the evap canisters crack on these cars. There is not way it has had that many vent valves go bad as far as part #'s I have no idea what's right or wrong I just fix them I don't look he parts up. They could be the same exact part just one has an AC Delco part # and one an actaul Gm dealer part # a lot of time they are. Hope that helps but with out seeing it I can't tell you exactly what the issue is. good luck :-)


---------- FOLLOW-UP ----------

QUESTION: Hi!

Thank you so much for answering my above question.  Life got busy and I still haven't been back to my mechanic to address this issue yet again.

However, I have an appointment tomorrow.  I believe the code was 455.  If you can tell me what part(s) to have him check/replace in addition to the canister vent valve so we can get to the real root cause I would really appreciate it!  And if your recommendation resolves the issue I will happily make a donation via paypal to thank you for your time in helping me!!!

Thanks,
Lori

ANSWER: a 455 code is a NON vent when commanding to vent. The vent valve is the most common issue with these besides a gas cap. If it had a rotted out filler neck it wouls set a p0442 code which is a small leak. if the canister was bad same thing a po442 would set. Now it could have a bad Purge valve on the enegine meaning the engine computer is commanding it on but if it's stuck closed or it's resisticted it could cause a 455 code. Odd/rare but I have seen it happen on these engines more common on newer ones then that. Hope that heps you out. Good luck!


---------- FOLLOW-UP ----------

QUESTION: Hi Todd!

I think we are finally getting somewhere now.  I just got my car back from the mechanic.  They were unable to do any work today but at least they were able to diagnose so that when I take it back in 2 weeks they can start working on it right away.

So here are the codes that the car now has and the notes I tried to take as they were telling me about it:
PO446 - they said vent control?
PO452 - they said pressure sensor low or high?
PO453 - they said pressure sensor low or high?
PO455 - they said evap large leak?

They told me the following:
1. Go get a new gas cap (one from the dealership, not aftermarket)
2. When I bring it back they are going to drop the gas tank and check the fuel tank pressure sensor.

Any additional advice you have based on this new information I'd really appreciate!

Thanks!
Lori

Answer
If the pressure sensor codes are set I would venture to say that the sensor is skewed high or low if it happes either way it can set false Evap codes like the 446 which is an odd code for this car. Also the pressure sors are a bit odd on that year of that car older ones yes not that common on a 2004 But I have seen it. good luck :-)