Not your average CEL question...

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KMeloney

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Hey all,

I've been documenting when I've gotten a CEL (same P0442 vacuum leak code each time), and I just got another one within a month. Well, my truck has been running like crap for a while now, and so I'm concerned as to what exactly is going on.

My main questions: Can the cause of the CEL and same code be cause for the truck to run like crap? And if so, what, exactly is going on?

I'm not going to clear the code this time. Instead, I'm going to take it to the dealer while the code and CEL are present. But I'd like a sense of what can be going on here to cause the constant CEL.

I've been led to believe that the gas cap can be the cause of this code (P0442, I think it is). But would that also cause a chugging sensation on deceleration (between 40-25 mph)? For the record, in that mph range, when coasting down through that speed range, I get the sensation you might get in a standard-shift car when the car is in too high of a gear at too slow or a speed, when the car may start to buck. The fact is that I don't know if the issues I'm having are all related, or if some are tranny issues while others are engine and/or drivetrain issues.

I just want to be armed with some more info before taking it to the dealer. As you can imagine, I want the problem(s) fixed the first time, and DON'T want to hear that they just cleared the code, and that they couldn't replicate the problem(s).

If anyone has some more insight into a reoccurring CEL with the same P0442 code, and this chugging/bucking sensation, I'd love to hear about it. It's driving me nuts. (If the low-speed bucking sounds completely unrelated, I'll take any insight into that, too.)

Thanks!
 

Faceplant

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Hmm. You may have a BAD gas cap if you keep getting that code, or there is a cracked or loose line in the vac system under the hood. The decel issues sound more transmission related to me. I have noticed some annoying clunking in my 08 LTZ when coming to a stop. Not sure if it the same issue you are experiencing, but mine definitely feels/sounds trans. related.
 

jcp21

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Hey all,

I've been led to believe that the gas cap can be the cause of this code (P0442, I think it is). But would that also cause a chugging sensation on deceleration (between 40-25 mph)? For the record, in that mph range, when coasting down through that speed range, I get the sensation you might get in a standard-shift car when the car is in too high of a gear at too slow or a speed, when the car may start to buck. The fact is that I don't know if the issues I'm having are all related, or if some are tranny issues while others are engine and/or drivetrain issues.


Thanks!

I have this problem as well on my 2009 Yukon. The dealer can never replicate the problem. The last time i brought it in the updated to computer. Seems to help but still not fixed. Anyone else have any suggestions?
 
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KMeloney

KMeloney

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I have this problem as well on my 2009 Yukon. The dealer can never replicate the problem. The last time i brought it in the updated to computer. Seems to help but still not fixed. Anyone else have any suggestions?

You too, huh? Geez. And yours is an '09, too. Wonder if that has something to do with it...

Do you also get a repeating CEL/same code, or just this same chugging sensation?
 

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