I Have a 1998 F-150 Lariat x-cab with a 5.4 and my check engine light keeps coming on. I put 2 new O2 sensors in it about 2 months ago and then about 1 month ago, the light came on. I have hooked it up to the computer and it does not show any code. I do a reset and the light stays off for about 1.5 weeks and then it comes back. I've reset this 3-4 times now. Can anyone help. I used a snap-on computer, not a cheap one you buy in a discount auto store.

 

I'm not trying to be be a smarty, but check your fuel cap, make sure you're putting it on right also...arrow at top, turn right.

 

Here in Michigan AutoZone has a program where if your "check Engine" light is on, you can come to them, and they will check your vehicle for no charge and let you know what the problem is. If you have an AutoZone where you live, check and see if they offer the program.

 

I forgot to mention that I changed my gas cap and also checked it for problems.