Question

I have a 2005 Mitsubishi Lancer Evolution 2.0L DOHC and OBD scanner shows P0420 twice, what does it mean? changed front o2 sensor and catalyst

Comments

i changed the catalyst numerous times and o2 sensor (bank 1) once but codes still there what do i do next?

Answer 1

First, this code is for the converter right off the exhaust manifold. If you replaced the second converter under the car the code will still show up.

Second, the rear O2 sensor after the converter is the one that reports this code to the ecm/pcm. If you are going to change an O2 sensor to try and resolve it, it should be the rear sensor and not the front.