I have been getting p0137 138 139 and p0157 158 159 since I bought my 07 Nismo. I just kept clearing the codes every 150miles or so, thinking it was my AAM test pipes. Today I finally removed both rear o2 sensors and this is what I found...










The previous owner tried a very poor attempt at pig tailing the wires. It was an electrical tape disaster!

Would this be causing my downstream codes to be triggered? The AAM test pipes have an extended o2 bung that keeps the sensor away from the exhaust stream, can this act like an o2 cheater device? Or do I need to buy 2 spark plug foulers?

 

I would get a new sensor.

I would order from Z1 with the O2 extenders. I still got the code on my AAM test pipes with just connecting the sensors directly to the extended bung.