My 2003 X had CE light, I pulled the code with my OBII scanner and it came up with P0155, 02 Heater circuit, Bank 2, sensor 1. I cleared the code, but I assume it will come back and if it does, there is a bad 02 sensor, correct? Which one is bank 2, sensor 1? Also, my experience with 02 sensors is your better of buying OEM, is that the same for Ford?

 

Code came back today. Anyone know which one it is and should I buy a OEM one?

 

Anyone? * Crickets *

 

Bank 2 is the drivers side, cylinders 6-10. Sensor 1 is forward of the Cat. (not sure if you would have any post Cat O2's). How many miles do you have? Yes, this could mean that the sensor itself is bad (at least the heater circuit). Make sure the harness looks ok and if it is I'd replace the sensor. As a check you could swap the suspect bank 1 over to bank 2 (and vice versa) and see if the code follows.

 

Did a quick search on partsguyed's site and it looks like $60 a piece for the OEM one so in this case I'd go with OEM. Sometimes OEM is very expensive on these things and I use Bosch universal ones. I'd go ahead and replace - the heater circuit heats up the sensor so it works quicker on cold starts and if bad will just continuously set off the code. You may end up with driveability issues and may even see mileage drop some as the fuel mixture could be thrown off. Recommendation - soak the sensor overnight a couple of times with a penetrating oil and buy the special socket. It's not that expensive and makes the job MUCH easier.