My wife called me this morning and said that her truck "Service Engine Soon" light came on. I've read that if oil is low it'll trip this (not sure if that's correct) however, oil level is fine. Read that carbon/gunk blocks throttle body and/or intake. Or could it be something else? Not sure where to start first, any advice would be helpful. Thanks in advance.

 

I dont think you can guess what it means... probably hundreds of different posibilities? Alot of places like advanced auto parts will run a free diagnostic. My light came on and was on for a few years before I checked it. It showed up as bank 1 too lean. But after I reset the computer it has gone away and never came back. I got a '99 4.2 also.