PCM Diagnostics & Tuning - P0420 w/O2 Sims???

I just installed the Hooker ORY pipe on my longtubes and I'm getting this code again. I got this code before with high-flow cats, but now I have O2 sims (brand new) and no cats. I thought the rear O2 sims would take care of this problem. BTW, I'm also getting the P1133 (insuf. switching B1S1) code.

Thanks for the help,
Joel

Not sure about the P0420 code, but as for the P1133, that indicates a problem with the FRONT o2 sensors, not the rears (which are now sims).

Check out your front readings with autotap and see if one of the front sensors died or isn't plugged in.

HTH,
Drew
'00 Formula WS6

Insufficient switching of your O2's usually indicates an exhaust leak exposing the O2 to fresh air.

Having this follow your ORP installation would lead me to believe that it is an exhaust leak.

Oh yeah, you should probably replace that O2 sensor as well. It could have gotten gunked during the install which could be causing the problem as well.

Thanks for the replies. I know that the 1133 code is probably an exhaust leak or bad front O2, but I was more confused about the P0420 code. That's the one I can't figure out-any ideas??

Thanks again,
Joel

How effective your CATs are working is determined by a relationship between the front and rear O2's on one bank.

Being you are running O2 sims with a bad front O2, I'm not surprised you got an odd O2 code.
Fix the front O2 sensor first. Odds are both codes will clear and stay clear.