I have a 2001 F150 XL with 4.6L V6 and 5 speed manual transmission. Fuse 23 HEGO sensor continues to fail. My owner's manual says HEGO sensor is only on Automatic vehicles. Is this circuit used for something else on 5 speed models?

Thanks,

 

There is no difference in the O2 sensor wiring between the manual and automatic-equipped 4.2L engines. You mis-read the manual. It states that F23 supplies the O2 sensors .AND. the automatic transmission (if you have one which you don't).

Check the O2 sensor wiring harnesses to see if one is laying on the exhaust or front drive axles if you have 4x4. If you've had ANY exhaust, suspension, clutch or transmission work done recently, a sensor harnesses likely got mis-routed.