Why would a 1998 GMC Jimmy engine light come on?

I don't know. but for my VW, the service rep said that it is a reminder for routine engine maintenance. if its flashing,,, then its a problem he said The short and sweet is that something is wrong. I'll cut and paste a reply to an Olds Silhouette driver who asked a similar question. Here goes, see ya at the bottom: The quick, dirty, and cheap answer is tighten your gas cap until it clicks at least 5 times. Within one or two days the vacuum in the gas tank will build up and reset the code. The not so cheap answer is take it to a dealer with a blank check, he'll tighten your gas cap and charge you $150. Or you can buy an OBDII Code reader or better yet a decoder that hooks to your car's computer and reads out your engine diagnostics real time. OBDII stands for OnBoard Diagnostics level 2 and replaced the older OBD1 around 1996. It tracks hundreds of items such as ignition timing, fuel trim and pressure, the number of times your Oxygen Sensor transitions from rich to lean(I got that one)and a list longer than your arm, including loose gas caps. It's a phenominal system which can even tell the police how fast you were going and if you applied the breaks before you plowed through the front window of that car dealership you love so well. The real problem with this system is that there is no way for it to tell you whats on its mind without an expensive interface that the dealer has. Until now that is. Take a look at http://www.scantool.net/, they sell a low cost OBDII decoder which will read the codes, reset the MIL(Check Engine Soon) Light, and give you data to help you determine what's wrong (loose gas cap?). It runs on an older PC or Laptop which allows you to get on the fly readings(you read, someone else drives). It's well worth the $100, get together with your family and friends everybody chip in 20 bucks and an old laptop(386 is OK)and your the hit of the neighborhood. Only trouble is that each scantool does only one type of OBDII output. Ford, GM, and Chrysler/foreign cars are all different. There are other decoders that handle all three systems but their more expensive. Do the cost/benifit analysis to see if you want a single or universal system and how much the share will be. Do a Google search on ODBII, and pick the reader you want. Hope it was just the gas cap. 94 Get smart, get even and, even if you don't want to do the work yourself be informed. A few years ago I paid over $900 to have a mechanic tell me "Welp, I just don't know". I got mad, went on the internet and found the information on the Central Port Injector problems that Jimmy's had and fixed it myself in a couple days. Whenever possible I buy the parts and take them to the mechanic. The parts store will charge you a half to a third of what the mechanic will charge and all you have to cover is the labor. If you have the time check out www.Rockauto.com, they have the best prices on parts for cars from Acura to Yugo and several I've never heard of, ever heard of a Lada Samara. If you have the time for shipping you can get the great prices on quality parts. Hope this explanation helped, see ya 94

Answer:

I have the same problem with my 98 jimmy. Apparently there is a problem with the poppet valve in the fuel injectors. there's a tsb out, and actually a recall in california. the solution is to COMPLETLY redo the injector system about 1200$ is the estimate I received. however, i located which cylinder was misfiring and replaced the fuel injector (70$) seemed to fix it.

Answer:

When the Engine light started coming on last year in my 98 Jimmy I checked the manual and it says the gas cap is not on properly. I took it off and put it back on and after driving for a minute the light went out. So far this has happened to me 3 times. Well worth checking that before starting any work on it.