check engine light but running smoothly, gas mileage normal use, great acceleration. changed gas cap several times, still same OBD 0402. is there a cat converter problem?
P0402 is an exhaust gas recirculation system fault, are you sure that was the fault? You wouldn’t replace a gas cap for an EGR fault.
I don’t think you have a V90, can you post a picture of the vehicle?
I am only seeing the V90 in years of 1997, 1998 and 2018 and up…
Based on you not knowing what you drive, which makes a BIG difference when buying parts, and installing multiple gas caps, then asking if it is a catalytic converter problem, all over an EGR system fault code, I am recommending taking your vehicle to a professional automotive repair shop for a proper diagnostic and repair…
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The OP may have fat fingered the model year too. But yeah, we need clarification.
p0402 means excessive EGR flow, which often causes very noticeable engine performance problems, stalling at idle/stoplights etc. Are you experiencing any of those symptoms?
p0420 refers to a problem w/ the catalytic converter. Suggest to double check the error code.
For crying out loud George do you ever read anything before you post your guesses?
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You beat me to it…
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Code clarification is needed. But because a loose/bad gas cap can set a code (such as P0456) if you ask around among people who don’t know anything at all, one of the things the unknowing say is “oh, the CEL can just come from a bad gas cap.” (I think some people think that’s the only thing it means).
So that might be why the whole gas cap thing entered the convo.
Funny - but not so funny - story. Sometime before I had a code reader, I had a CEL pop and went to one of the big box stores to get the codes read. Before even reading the codes, the guy said “It’s an O2 sensor. What else could it be?” I kid you not. Old guy. Struck me as probably a retired old shade-tree who spent most of his shade-tree time dealing with cars pre-OBD era. It wouldn’t surprise me if he could rebuild a carb (or starter or alternator), but he obviously knew nothing at all about computers and OBD and whatnot.
Question for the pro mechanics here: Do you ever have customers tell you something like this, engine still runs like new on an 11 year old car with a check engine light, but you find out later there is actually a very noticeable engine or drivability problem? And presumably the customer is trying to minimize this b/c they think that will lower the estimated repair fee?
Maybe they just have not noticed slow degradation of whatever has become so bad that they are brining it to a mechanic.
Yes, that’s a possible alternative. In any event I expect is is pretty common for pro mechanics to discover a car’s performance isn’t quite in the condition claimed during the owner’s initial description. It’s a natural response to problems, we all do that I expect for many of our problems: For example the chain smoker who says “I have no tobacco problem. I can completely give up smoking anytime I want.”
An EGR malfunction won’t necessarily cause drivability issues however the next person might notice a high idle speed.
After reviewing the bickering will the OP want to join the conversation? Seems most do not. Many threads seem to run afoul, there must be better forums out there.
Concur, I’d expect for there to be some sort of noticeable low rpm effect if there is really excess egr flow. If there isn’t any effect at low rpms , that would be diagnostic too, as it would indicate the problem might be with the flow sensor, not the EGR passageway itself. I’d certainly expect a pro mechanic to ask about low rpm operation if their customer came in with a check engine light and excess egr flow code. Even if the customer said the engine was smooth & accelerating fine.
The very few new posters here who stay for any length of time seems quite concerning. Free information after all, what’s not to like? But it appears new posters here must not be feeling the “free-information” spirit. As far as other forums, my guess is a lot of folks owning an Audi say prefer Audi forums rather than general purpose forums.
In situations like this, I’ve found the reason is because the customer simply wasn’t able to accurately describe the situation, nothing more than that
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