1997 VW Cabrio P0422 Code: Diagnosis and Solutions for Catalytic Converter Efficiency

Model: 1997 VW Cabrio Fault Code: P0422 Posted: 2007-03-09 11:27

Hi everyone, I'm a member of the VW Cabrio community and have been struggling to resolve a persistent P0422 diagnostic code. I recently joined this forum hoping to find a practical solution. The car continues to show a P0422 code, but engine performance is excellent—no rough idling, smooth acceleration, or any noticeable drivability issues. During my last tune-up, I replaced the spark plugs, wires, distributor cap, rotor, and both oxygen sensors. Additionally, I recently installed a new catalytic converter (from Autohaus AZ) and upgraded to a stainless steel performance exhaust with a larger diameter than the original. The catalytic converter is slightly smaller in size compared to the OEM unit but otherwise matches in specifications. Despite these changes, the P0422 code persists. I'm not concerned about engine performance—only frustrated by the persistent check engine light. Any insights into potential causes or troubleshooting steps would be greatly appreciated. Thanks in advance, Bob