A/F and O2 Sensor
Okay I hope I am not hijacking this thread.
I have 2000 4Runner V6 3.4L 4X4 Limited - CALI - (2) CATS
Got a P0420 Code was going to replace the downstream O2 Sensor behind second CAT right before muffler and if that didnt work I would try replacing the A/F Sensor up front...
