01Screw5.4

I don't mean to jack the thread from the OP, but today while driving I noticed the service engine soon light as well. It couldn't have been light up for very long before I noticed, and it wasn't flashing just a solid light. Everything seems to be running fine, no shakes or funny noises. I was wondering if anyone has had this happen and if so what was the problem? I don't want to pay the Ford dealer $100 just to take a look at it, and our local Ford dealer is sketchy at best. Any opinions?

2003XLT

What was your code? The service engine light can come on for a loose gas cap broken filler neck misfire transmission codes it's endless all those expensive little sensors you have all communicate with the PCM which somebody already explained what it is but think of it as your trucks brain and it is constantly checking all
The sensors in the car for any alterations or unusual increase or lack there of performance an any small vacuum leak can set it off

Idk if I missed something in your post but in order for anyone to help you you need to get our truck hooked up to the obd2 port and someone to pull a diagnostic trouble code (DTC) from your computer it will be most likely a "P" then a series of 4 numbers

i.e. P0420 which is a universal "oh crap" I need a catalytic converter code

Any autoparts store usually will have a free code read for you and most places like autozone can pull a brief description of what the code is but if not you can always google it because there is a slim to none chance you are the only one who has ever had that code

Also come back here and let us know how you make out

Good luck!!