I have a 1998 Chevy Venture with a code po420 set. I have replaced both oxygen sensors and the catalytic converter. The code was cleared by the muffler shop when they replaced the converter and stayed off for about one month. It came back this week. Does anyone have any ideas on what could be wrong? I know this code is telling me about the converter not operating at peak efficiency. Thanks, Terry
- posted
19 years ago