Error Codes P0420 + P0422
I have had the same 2 error codes re-appearing on my 2001 Forester for about 2 years now.
My mechanic told me it's the Rear O2 sensor, and that Subaru O2 sensors are notorious for being fussy. He said just resetting the code would solve it as long at it only occurs once in a while. The error codes would light up every 6 months or so and I would just reset them.
Now the same two codes are kicking in within 2 weeks of a reset so I am trying to get them resolved.
The codes are:
P0420: Catalyst System Efficiency Below Threshold (bank 1)
P0422: EVAP Control System Leak Detected (Small Leak)
I am now in a new area and went to a mechanic who wasn't familiar with my vehicle history. I explained my situation and mentioned to Rear O2 sensor issue of the past. This mechanic read the codes and said that it was not the rear but the FRONT O2 sensor since "bank 1" was part of the message.
They replaced my Front O2 sensor, and the same codes kicked on 2 weeks later. They are now telling me that the second code has to do with a leak in my fuel line, probably at the gas cap or the down pipe to the fuel tank (I'm sorry, I don't know the technical term), and the first code has to do with a bad catalytic converter.
I already paid for an O2 sensor to be replaced that I apparently don't' even need since it didn't fix my codes, and I'm affraid they are just taking me for a ride now. Can anyone explain this to me?