Ok Guys- here's a good one for you. CEL light
 

Hey guys, I have been modifying a friends 350z, and am having a hard time with a check engine light. First off, let me tell you that I am NOT an amateur who doesn't know how to use the search. I am a mechanic for a living, and just wondered if any of you have this same problem.
I installed a set of kinetix high flows on a 2004.5 anniversary. We immediately got a check engine light. This is not normal, and I have never gotten a light from high flows on the Z cars. We inspected the cats, and found one of the welds leaking on one of them. Great, we found the problem, NOPE. We fixed the cat and re-started the car, same problem.
I figured, ok, we will do the non-fouler fix. This still did NOT clear up the problem. We can get the light to come on exactly the same way everytime. Drive the car until operating temp, turn it off for a few minutes and restart. In less than a mile the light comes back on.
I did run codes on the car and they are as follows:
P0057 Bank 2 sensor 2
heater circuit low.

Do any of you have ideas????
Thanks

Could you have dropped the sensor in the change over ? They dont like being dropped.
Clear the codes & then swap over the sensors to see if you get a P0037 bank 1

Didn't drop the sensor. I also thought about the swap idea. Good thought, will let you know.