P0420 investigation

[beerdog]

Hi all. My car started throwing a P0408. This is related to the cats not working. The challenge here is my car has no cats. The rear O2's are removed. Every thing is turned off and adjusted in a tune that has been working fine for a long time. The car seems to run fine. Any ideas where to start? I was thinking maybe one of the front O2's has failed.

 

[driller]

Hi all. My car started throwing a P0408.

Typo?

Honestly, if it were me, I would replace the O2 sensors. Even without the rear O2's, the front O2's monitor the A/F ratio and the PCM adjusts the fuel trims accordingly unless you run open loop full time. You could datalog the fuel trims but it likely would lead to the same conclusion.

 

[beerdog]

Thanks. I cleared the code to see if it comes back. The O2's are easy to replace and I got 10 years out of them so I can' complain. I may even have a few new ones in my parts stash.

 

[tixer]

Good to see you're still out there and rockin' the Mark, beerdog!

It's been too long..