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Audi A4 1996-2001, S4 2000-2002 (B5) Check Engine Light P0422 HELP


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Last Post: Apr 6, 2013 4:53 AM Last Post By: FKH161
JV4

Posts: 1
Registered: 04/05/13
Check Engine Light P0422 HELP
Posted: Apr 5, 2013 4:29 PM
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Hello. Just bought an A4 quattro 1.8. The check engine light came on and code read P0422. I changed the pre-cat 02 sensor a week ago and erased the code. It just came back on yesterday with the same code. Could this be the post-cat sensor needs replacing as well? Is the cat bad? What is the most common repair? Any help would be appreciated. Also, car has aftermarket intercooler and cold air intake which i intend to replace with stock parts.
FKH161

Posts: 7,661
Registered: 12/29/05
Re: Check Engine Light P0422 HELP
Posted: Apr 6, 2013 4:53 AM   in response to: JV4 in response to: JV4
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Cat efficiency is monitored via rear O2. If the sensor switches between lean / rich too often, that usually indicates that the cat is bad.

Make sure that your thermostat is ok, as a cooler running engine can prevent a cat from lighting-up, which will also set a cat code.

I'm not 100% sure, but 10yr/100k km warranty on cats.

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