Found this loose connector laying under the intake manifold. Harness traces back to the main harness on the firewall beside the brake booster. I can't find what it plugs into. Anybody know? Thanks Todd

 

Knock sensor I believe.

 

Wouldn't an unplugged knock sensor throw a code? Have to look up where that sensor is located.

 

How about an under hood light?

 

Does it go to the Flux capacitor? I donno!
LOL, Sorry I just couldn't resist.

 

Any other thoughts? Does anyone have an underhood light? Does the plug look like this?
Trying to solve this mystery as part of a bigger 10mpg problem.

 

Heated PCV connector? I dont have an F150 or a heated PCV valve but I know some Ford trucks do and if so then the sensor is probably on the drivers bank of the engine and kind of looks like an oxygen sensor with a plug coming out of the end it of it or an electrical connector on it. Also does the truck have an oxygen sensor at the back of the engine?

Just some ideas

 

just went and checked on my 2002 4.2, it is the hood light wire, would run under the insulation if ya got any, bout 2.5 - 3ft long excessively taped directly by ford

 

Thanks for checking that WickedKlown, saved me a lot of head scratching. I will have to look elsewhere for the mileage issues.

 

Well, wickedklown was bang on right. Looked up instead of down and low and behold, there was a hood light without a harness connection. The push clips that held the harness against the underside of the hood had broken. Clipped the harness back into the light (it works) and ziptied the harness back onto the pushclips. 5 minute fix.

Thanks again for all of your help!

 

Not a problem. Glad i was able to help ya out... as far as mileage kinda hard to tell.. i know my 4.2 has the secondary butterflys on the intake and when the plastic clip broke my mileage went to crap but also gave me codes. .just a idea there... not sure what all years even got the secondaries