I have doen the following to my truck in the last month:
kegger mod
180T stat
plenum fix
timing chain
SCT tune (currently running 87 octane tune)
removed cat
Using 2 anti-foulers on the rear O2 sensor

My truck just threw this code today P0138. I replaced my cat with a pc of straight pipe and welded 1 of the antifoulers to the pipe, threaded the other one into that with the center drilled out to 1/2". and screwed the O2 sensor into that one. I did this about 2-3 weeks ago. Havent had any issues since I did it until today. I cleared the codes and it has not come back (yet).

any ideas?
Thanks
Matt

 

Did you ever reset the pcm when you did it the first time ? could very well be that the comp is just now throwing codes.

If it pops back on then you'll know it's something different

 

not sure what your asking, but... Battery was disconnected for 2 days when I did the plenum repairs etc. When the check engine light popped I did not disconnect the battery, i cleared it with the SCT.

 

The problem is the "anti-fouler". Your cat is gone so the rear O2 sensor reading is whacked. That's what a P0138 is all about ;-)

I guess the other thing is that the wiring to this anti-fouler thing is incorrect.

 

The anti fouler thing is a proven trick to fool the computer into thinking the O2 is reading correctly. Do a search here for it. Many have done it with success. The only wiring going to it is the O2 sensor wiring.

 

update.
A week or so after the truck started throwing O2 codes i crawled under the truck to check things out. I found my muffler was loose. I had recently installed the straight pipe and clamped the mullfer, Apparently there was not enough contact between the muffler and the pipe.I welded the muffler to the pipe and the truck no longer throws any codes.

 

Good! glad you got it figured it dude

 

Thanks!
you still need the hub?