code P0420

[ldhwade]

Help!!! My service engine soon light just came on. Pulled the code and came up with P0420..I've found what the code means...but my question is what do i do to fix it.


Thanks in advance

ldhwade

[maxwedge]

Originally Posted by ldhwade

Help!!! My service engine soon light just came on. Pulled the code and came up with P0420..I've found what the code means...but my question is what do i do to fix it.


Thanks in advance

ldhwade

Please post year and engine!

[ldhwade]

It's a 2001 grand am....4 cylinder sorry i left that out of the first post.

[maxwedge]

This code can be a complex diagnosis, sometimes cat, some time post cat sensor sometimes software reprogram, sometime excessively lean mixture, google the code or search this site there are lots of good tech articles on this that have lengthy details on the issue.