I have a 03 F150 with the V6, and last winter the SEL came on. It started out intermitedly, but by jan. it was on all the time. On top of that i went from 23mpg to 18mpg. My code reader displayed these codes: p0171, p0174, p1131, p1151. I know what they mean, but don't know where to start. Went to dealership to talk, they said it was "sucking in air somewhere- vaccum hoses." Wouldn't be the MAF, and highly doubted that 2 o2 sensors would go bad at the same time. Does anyone have a clue, or at least an idea? It is not the IAC, & can't find the PCV valve. Any thoughts???

 

The PCV valve is located in the back of the passenger side valve cover. It's a small little 90* elbow that can be a pain to grab if your arms aren't long enough. lol

The intake gaskets on these engines are supposedly cheap, and depending on what style intake manifold you have (aluminum or plastic), the gaskets will expand more than they should, causing a small leak every so often when they expand/contract.

 

I just got done working on the truck tonight, and sprayed the motor with WD-40. Nothing happened. Just ran the same. Checked the bolts on the intake, front seemed very loose and corroded, so I tightened them(snugged). I decided to unplug the battery. Let it sit for dinner, then went back out. Read something that turning the headlight switch on then off will delete codes in PCM & tried it. So far it worked. Took it for a drive for 30 minutes, sounded a little better. Then I shut it off, and started it back up and let it run for 10 minutes, still didn't come on. Don't know yet if it worked or if it is just another trick up its sleeve!!??

 

my dads 02 ford f150 4.2 ..for about 4 years in a row it would throw these codes around christmas ...and i would clear them and they would come one maybe 1 more time during the winter ...always ran good though..now the lights on for good and its starting to run a little rough...i have not even worked on it i put plugs and fuel filter on at 36k...and hasnt been worked on since then its now got 150k....haha...so i might try tighting up the bolts if it fixed yours..keep updating haha

 

Good news! Since I tightened the intake bolts, and reset the computer, the SEL still hasn't come on. The truck has gone about 500 miles, and still hasn't come back on. I won't be able to see if the gas mileage has bounced back because my sister drives it now.... Runs great, hope it lasts!!!

 

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