Check engine light came on...

[Alan06SUT]

Over the past couple of days, I have noticed some hard up shifts once the truck is good and warmed up. Today the check engine light came on while driving at about 80 on the highway. All vitials are fine, oil, temp, trans temp, etc. Nothing is leaking, and no other symptoms are noticable. I have driven it around some and the engine light still comes on each time I start it up and drive around. I will be taking it to the Stealership tomorrow but I wanted to get some possible ideas as to what it could be so I dont have to go back several times!!!

TIA.

[timgco]

POS HUMMER.

Have you checked your air filter, do you have an aftermarket filter? Where you in a lot of mud. There are sensors that can get plugged up.

Sice you now have the 37's, you may want to look into a Superchips or Hypertech programmer. You can adjust for tire height (not that it's off much) but you can get more driveability with the shift points and more importantly, you can check codes when things happen like this.


I wonder if you have an O2 sensor bad or clogged with dirt or something.

Try running your truck with the engine code on and hit your OnStar button and ask them for diagnostics.

Good luck.

[Big Z]

Make sure the gas cap clicks, and trans level is topped!

Superchip is a must with oversize tires (a must anyway ) But,--I'm a believer!.....especially After Chipping Lil Ugly's 8100/Allison

[Alan06SUT]

Thanks. I'll look into the superchip. I'll reply back once I've got it handled. .

[Alan06SUT]

Well, It had to stay at the dealer. It was a slipping transmission code. He will know what has to be done tomorrow. New tranny????

[ROX]

Good luck with that. Did you show them the pics of you towing 4th avenue behind your truck a couple weeks ago?