P0420 Fault Diagnosis for 2000 Daewoo Nubira: Exhaust Leak Fix and O2 Sensor Check
I own a 2000 Daewoo Nubira sedan and am currently experiencing a P042-0 diagnostic code. After inspecting the vehicle, I identified a loose exhaust pipe, which has now been securely repaired. Based on several forum discussions, there appears to be a recurring issue involving either the catalytic converter or one of the two oxygen (O2) sensors. Although I occasionally detect a faint exhaust smell, I am considering addressing this first by checking the O2 sensors before making any costly replacements. My main question is: Am I taking the correct approach in troubleshooting this problem? I want to avoid unnecessary part swaps and would appreciate guidance on the most cost-effective path forward. Thank you for your insights.
You're on the right track. First, ensure there are no exhaust leaks—this is a common cause of P0420. If the O2 sensors read normally, the issue is likely due to a failing catalytic converter. Replacing just the cat will be more cost-effective than swapping out multiple components. Good luck and feel free to update us on your progress.