NEED HELP ON FIXING MY FORD F-150 XLT TRUCK. I HAVE
A CHECK ENGINE LIGHT ON MY DASHBOARD. DO ANYONE
KNOW WHATS THE PROBLEM BEFORE I TAKE IT IN AND
HAVE IT FIXED.

 

Just had the same service engine soon warning light on my 99 F150 XL. The fuel cap not being tightened securely was the problem. Instead of waiting for the 3-5 start/warm up cycles for the light to go out, I tightened the cap and reset the computer. did that by removing the negative battery terminal from battery and turning on head lights for about ten minutes. Turned lights off then reconnected the battery terminal. Problem was corrected.

Thanks to this page because I read that tip here. Saved a trip to the dealer.

 

Mine has come on three times recently. First time they did a long expensive diagnosis before discovering the problem was a $15 gas cap. Second time was within seconds of fueling up. I called my service guy and he said tighten the cap and after a few cycles the light should clear. I reset the computer by disconnecting the battery cable. It works just fine without turning on the light switch for ten minutes as is often suggested.
Third time the light came on was recently. I also had the brake and ABS lights on. They replaced some module that was tied in with the vacuum system. This also unexpectedly took care of the check engine light. Service guy said the leak in the vac system must have been causing the light to come on and was responsible for a minor rough idling, which disappeared also.

 

I just finished dealing with a similar occurance. Check engine light was on, gas cap was not secure so I made sure it was, disconnected the (-) battery terminal for a few minutes, reconnected it, started the truck and let it idle for a minute or two to let the computer re-learn it's stuff and away I went!! No more C/E light. Check the gas cap before shelling out $$ for diagnosis...

 

The Check Engine light is a "one light for anything" light. Even tranny problems will cause it to come on. But, like the others have posted, check you gas cap first. If it is still under warranty (you didn't specify year or mileage) and the cap is tight....let the service dept. take care of it.

 

Spoke too soon on previous message. Got a new CE light today. This is the third time recently that I have gotten one after the truck has been sitting, unused, for two or three days. Coincidentally, all three times have been at the airport while I was out of town but I know that has nothing to do with it, especially since this weekend it was at Hobby airport in Houston and the two previous times it had been at Houston's Bush Airport.
What would cause this to happen only when the truck is not run for a few days? It starts right up, runs great, but the CE light comes on after getting up to freeway speeds on the way home.
The last couple of times I have cleared the light by disconnecting the battery for a couple of seconds and the light never comes back on until the truck sits for a few days.
What's up with that?

 

Surely a code is being stored in the ECU. Disconnecting the battery will not clear the code (Federal regulation). The only way to clear a code (legally) is with a code scanner. I wonder if the stored code is making the light come on again. I would expect it to come back on sooner though.

 

gah said:
I kept thinking if it was something major it would come back very soon after clearing it. It only comes on after sitting two or three days or more.