2004 Audi Allroad Quattro Q&A
2004 Audi Allroad Quattro Question: check engine light
check engine light is on......scan shows 2 codes P0421 and P2197. replaced air filter today. praying it is not cat. converter(s).aceleration is perfect and I detect no foul odor from engine or emissions.Allroad did sit for 5-6 weeks and has 146K on it. Has been dealer maintained since new. Still runs perfectly Anyone have thoughts? Thank you all! - shark13
The P0421 is a catalytic converter related code all right, P2197 says an O2 sensor is stuck lean, fixing that code first may solve your problem because if the computer does not see a good balanced relationship between the O2 sensors it then assumes the cat is bad. Perhaps it is lean for a reason any way proper diagnosis is needed before replacing parts and use of a good professional grade scan tool may get to the root of the problem quickest. - patrick mannion
An O2 sensor can cause a false cat code. There is a procedure called "generating readiness" that will be required to detrermine O2 or Cat. If the Cat converter is marginal you would never know except for the chcekc engine light coming on. If the dealer determines that the O2 senswor is the problem, I would recommend replacing all four. - baccurate
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