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Discussion Starter #1
Hi all. I own a 1999 eldorado w/ 47K miles. Recently (about 5 months ago) I had my gas cap replaced because I was constantly getting the "check gas cap" message. It's happening again and this time the service engine soon light will not go off... Can it be that they (the dealer) gave me a bad gas cap to replace a bad gas cap? What can go wrong with a simple gas cap?

The following are the error codes I read from the vehicle computer:

pcm p0440 current
irc u1255 history
msm b2119 history
pcm?

If I were to approach the dealer with this problem, are they obligated to make it right since they tried once already to fix it (factory warranty expired last March)?

Is it possible to fool the computer into thinking I have the most perfect damn gas cap ever manufactured so it stops jerkin' me around?

Thanks in advance to all who make an effort with a reply.
 

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I'm not sure what the codes mean perse, but the check engine light is most likely separate from the gas cap. I have a similar problem with my service ride control message. Two dealers say it's nothing...just like your gas cap. So far I've lived with the message, but I'll probably have them disable it at some point. They could probably disable the gas cap message too. Also, maybe your Caddy isn't lying and gas is leaking around your gas cap! Check that out before you have someone kill that code. In the meantime, have them investigate the service engine' codes. probably a bad o2 sensor (the most persistent problem with eldos :()
 

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Thanks for the input Chuck. I've checked the gas cap every time I refuel. It seems perfectly fine. I even tried asking it very nicely to quit screwing with my vehicle computer but it ignored me.

Can anyone identify the trouble codes?

Is there a way I can clear the codes from memory to see if they return?

Can the gas cap sensor be disabled without affecting any other system?

P.S.. this forum is great! :bonkers:
 

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The two "History" codes are as follows:
U1255 = Class 2 initialization error
B2119 = Lumbar forward aft sensor failure
Don't sweat either of these, until they are current codes.
The P0440 is your EVAP system fault (your gas cap). THIS needs to be fixed. It could be a bad cap, or something as simple as a loose clamp on a line. Really not a problem either way.
 

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Discussion Starter #5
Kevin, sweet FTS!

Is there an easy way to test a gas cap?

Just out of curiosity, does anyone understand how the system determines that the gas cap is faulty? (aside from the obvious...) I'm asking because I have a feeling that the problem may still not go away by simply replacing the gas cap. Are there hoses, wires and hose clamps associated with the EVAP system that I can inspect? Where is the sensor located that signals the fault?

Thanks for the helpful advice.
 

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I think he has a red phone linked to the Cadillac Mainframe computer operator.
 

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mecheng said:
Kevin, sweet FTS!

Is there an easy way to test a gas cap?

Just out of curiosity, does anyone understand how the system determines that the gas cap is faulty? (aside from the obvious...)

Thanks for the helpful advice.

My guess there is some kind of sensor that detects whether the fuel system is pressurized. If it isn't then the warning. I suppose its easiest to blame on the cap but maybe there is a leak (opening) in the system somewhere else casing there not to be any pressure, or low pressure.

This is ALL speculative; just my guess.

As far as Diagnostic Codes go, try this link whenever you need to look up a code:

http://www.diagnosticdialog.com/LookupCode.asp

Good luck!

Oh! Yes you CAN test a gas cap. At least in California you can at any smog station.

..rickko..
 

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Someone correct me if I'm wrong, but from what I remember, there's a fitting under the hood and Nitrogen gas is pumped into it so a sniffer can check to see where the gas fumes leak. From that, the tech can determine where the fuel vapor leak is.
 

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One of the techs once told me that it usually isn't the gas cap, but if it is, hang on to your receipt. There's a 12 month, 12,000 mile warranty on it.
 

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Long shot but here goes. Check the neck that the gas cap fits into. Run your finger around the area where the o-ring fits into. Maybe some debris causing it not to seal? Maybe out of round if gas station attendant got rough with it? Worth a look.

Regards,
Rich
 

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Yeah i had the check gas cap come on for my cts and i was definatly suprisd...especially since the gas cap is perfectly fine....could it be something with my air intake screwing up the air fuel ratio and hence causing the problem????
:cheers: :thumbsup: :grouphug:
BTW POST 400!!!
 

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Yeap

Any problem in the EVAP system can cause the code. There was another mention on 'why cant these be built right'. Well, its your goverment. They are the ones that mandated OBDII. Stupid things like loose gas caps and vacumm leaks will trigger a code. There use to be about 50 codes on a complex car like Cadillac. Now there are about 300. Just for the powertrain/trans.

The one good thing about OBDII is everyone is using the same codes. Example is a easy PO300. This is for a random cylinder misfire. This code is the same thing on a KIA and Cadillac.

After these cars get 120-150k on them, I cannot see how you will be able to get the check engine light to turn off.

This place is turning into Japan. There, you are very, very, very lucky if your car passes the 30k goverment inspection. Nothing that a new car wont fix.

Logan
 
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