I have a 1996 F150 with a 4.9 I6. It keeps throwing a code for the O2 sensor heaters. I have changed all 3 of the sensors out and reset the CEL but it keeps coming back. Does anyone have any ideas what may be causing this?

HL

 

HL, if you have the four wire sensors, one of the wires is for the heater ground circuit. On most Fords, it will terminate to a bolt somewhere on the rear of the engine. Maybe you have a bad ground where it terminates? I think the ground wire is yellow (maybe with a stripe), but I'm not absolutely sure.....