I installed a mac off-road y-pipe on my 99 Z and that night I set an ses light about a multiple cylinder misfire (P0300) and 2 P1153 codes. Took it to a friend a couple of days later, and he found that the retards that installed it put the right O2 simm in the front instead of the rear. He fixed it and everything was fine, went to the track that night and got some nice gains, car ran great. Then a few days later the light set again and this time it's giving me two P1133 (HO2S Insufficient Switching Bank 1 Sensor 1) and two P1153 (HO2S Insufficient Switching Bank 2 Sensor 1). What the hell is goin on, will this affect my performance? I think it's runnin rich, cause you can smell it, but maybe that's just b/c the cats are off, cause it's not that bad, like not unbearable. Thanks in advance for the help guys.

 

If you have taken your cats off did you get some O2 simms for the rear O2 sensors. If not that is what is most likely causing your ses light.

 

have your friend recheck the wiring maybe something came loose.

 

I totally agree, if you have no cats you have to run 02 simms in the rear!

 

yes, I have o2 simms. And I don't think anything is wrong with the wiring, my friend checked it and it's fine. Also, it's weird, the light shut off for about two days a few days ago and then it came back on. I don't know what the hell it is!