P0131 O2 Sensor (Bank 1 Sensor 1) 3.3L

[Myrdhyn]

Ford recently replaced both of my CATs under warranty, and a few weeks after this it started throwing a P0131 code. Its intermittent with the weather, on damp days it tends to shut off on its own and stay off for a bit before coming back on.

I just climbed under the vehicle and checked the O2 sensor locations. Bank 1 Sensor 1 is a short way in front of the driver side CAT and not far from access, however the space available to work in is TINY.. Has anyone replaced this themselves? I can't find any videos on youtube of someone having done it on a 3.0L PIU

 

[Myrdhyn]

To answer my own question, its impossible to do this one at home. Because of the location and limited access I took it to the shop. Even they said nope, and ended up having to unbolt the CAT from the exhaust header to access it as you cannot get to it any other way.

 

[Myrdhyn]

OK, so this sucks.... New CAT and new O2 sensor and the computer is still spitting out the same code.

 

[t9087]

That code means your engine is running rich. I would check for vacuum leaks or something that is allowing more fuel than air.

You could also have faulty EVAP purge solenoid even though your not having an EVAP code.

Without a scan tool showing live data for the fuel trims, it’s hard to determine what is causing it.