Rmttex1212

The other day I was driving down the road when I noticed my CEL was on. I pulled the code and got p0420. I'm having trouble finding info on solutions since most of the threads are about lancers running an aftermarket exhaust system.

I have an 09 lancer with a PZEV flashed ECU.

Also, is their any way I can find out if its the cat or the sensor without replacing everything?

Jbone

From in my past this code usually comes from a bad oxygen sensor or one going bad. However this thread has some interesting info on it..http://www.evoxforums.com/forums/showthread.php?t=34136

oSHINSAo

Hello, what's the o2 sensor for code P0420 ?? Upstream or Downstream? and where is located?

Veronica

iTrader: (2)

It is the downstream (second) O2 sensor.


It is right after the cat converter.