Please, i need some help with this code, p0420. It keeps appearing even though I've got changed both the O2 sensors. My car is a 2003 Nissan Altima 4 cylinders. it has 130k miles. I'll appreciate any helping comment. Thanks #212 - willie - 12/04/2011 - 22:51Ran...
How the codes P0420, P0421 or P0430 are diagnosed: year, make and model bulletin P0420 Check Engine Light: What to check first, repair options 19-049 21-2381 1. Clearing the code and checking if it comes back: 2. Comparing the signals from the pre-cat air/fuel ratio (Front O2) ...