Questions & Answers for: Chevrolet Cavalier 420

DTC #420 on a 2004 chevy Cavalier Replaced the O2 sensor, now getting a #420 code after about 130 miles. Sometimes not for a couple hundred miles. Need to monitor rear HO2 sensor operation. Possible ...

i have 1999 chevy cavalier that has an engine code of 420 Code 420 is a catalytic converter is not working properly.Check the converter for leaks and the rear oxygen sensor for leaks.If they are good ...

...not pass the vehicle inspection report What was the code given.. 02 will mostly sensors.. Cat code 420 will need new cat And evap codes can b a couple different parts..need exact codes to tell what ...