Hi Guys,

I am in need of some help. My brother has a '99 TL that has had the CEL come on for the past few months. Error code P0420 comes up. He has already had the Cat changed and Sparks changed. Do you think it's the O2 sensors? Is there anything else it could be? Is this something that normally goes bad. I have seen some posts on here, but still am kind of stumped in our situation.
Thanks for the help.

 

Has he cleaned the EGR? That often causes that code

 

Most likely its your 2nd o2 sensor.