I am having a problem with a check engine light fault code p1151, lack of upstream heated o2 sensor switch, sensor idicates lean, bank 2. At first I thought it was a bad o2 sensor and replaced it out. Now I am finding that not the case. The sensor seems to be getting little signal(from my airfuel gauge which could indicate lean or something else wrong). The truck idles rough but runs ok once I get going. What could be wrong?

 

I have same error code. When I installed my long tube headers, I couldn't find wire harness extenders, so me and a friend custom made some. Now I have that error and my truck idle's funny. I finally found the extensions and should be in tomorrow. Will replace my 02's as well. I don't know what could be the problem with yours since you've replace it. I called my local ford dealer and they said I'd have to take to truck in. So much for that. Good Luck.

 

I made a search on the mustang site. Found lots of info. Try there.

 

changed my 02 sensors and problem solved.