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Engine Shuddering, Vacuum Leaks and Catalytic converter

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Engine Shuddering, Vacuum Leaks and Catalytic converter

Old 02-16-2010, 08:54 PM
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Join Date: Feb 2010
Posts: 1
Default Engine Shuddering, Vacuum Leaks and Catalytic converter


I was driving my car(2002 A4 3.0L Sedan) two days back and suddenly the CEL flashed a few times and car shuddered as long as the CEL flashed and then everything was normal again. Came back home and ran the engine codes. After numerous attempts to run the diagnostics (None of the inspection stations are able to connect to the OBD) I was able to connect once and here are the engine codes:

16815 - Warm Up Catalyst; Bank 2: Efficiency Below Threshold
P0431 - 001 - Upper Limit Exceeded
16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 001 - Upper Limit Exceeded
16688 - Cylinder 4: Misfire Detected
P0304 - 001 - Upper Limit Exceeded
16689 - Cylinder 5: Misfire Detected
P0305 - 001 - Upper Limit Exceeded

Took it to a local mechanic and they cleared the codes and told me that the coils were okay and that catalytic converter did not pass readiness codes.

Took it to the dealer, and they say that there is a massive vacuum leak and because of the unstable idling it is causing, they are not able to connect to the controller to see what the issue with the cat is. Unless they fix the vacuum leaks (~350$), I've been told that no tests can be performed to see if the cat is functioning properly or not.

By Apr-10 I ll be out of federal emissions warranty. Can someone pls suggest if I should be getting the vacuum leaks fixed at the dealer? or if these issues are related or not?

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