Truck engine

CMCCULLAH09

MEMBER
2004 GMC SIERRA
V8
4WD
AUTOMATIC
103,000 MILES

I have a 2004 gmc Sierra 1500 4x4. The check engine light just came on and I'm having a thousand different problems. It is spitting a black tar substance out the tailpipe, if I am not giving it gas it seems to loose almost all power. I have to give it more gas then normal to get up to speed. And not to forget it's sucking down more gas then normal. I live in Alaska if that has anything to do with it. There's also a strange odor that I can smell.

1 Reply

WRENCHTECH

MECHANIC
20,757 POSTS

The "check engine" light is an indicator for a system that monitors many electronic functions in the system, also called the "malfunction indicator lamp" (MIL). It can come on for any of hundreds of different causes from any of the systems that the computer monitors. Some are very important and can lead to further component or engine damage and some are emissions related not as serious but still a problem and need to be repaired.

Your first step is to have the computer scanned to retrieve the trouble codes that were set when the check engine light came on. Those codes will give you specific information about what the computer saw and will get you pointed in the right direction to find your problem. With a 1996 or newer and some 95 cars and you have an AutoZone or Advanced auto parts in your area, they will read them for free. Once you have these code numbers, we can be a lot more specific about what your problem may be.