It has the CEL light (been on) for the 02 sensor heater by the downpipe, dosen't affect driveability at all it even said it on the code scanner, same with my throttle position sensor code no driveability issues and says that. If I reset the code, it will stay off for say about 20-50 miles then flash back on while i'm driving normally. Any suggestions? Dosen't the 02 sensor near the downpipe mean it's a bad cat. converter i've heard I think?