In my '00 the gas gauge like to only show 3/4 or more. The fuel QTY used is true. I'm also getting a "check gas cap" message and I've played with the cap and no joy. Finally when I scan it it'* giving out a Evap system code-__ (I have to pull it again) But clearing the code shuts up the DIC message
SO
1- Are these realated? I think so but not sure how.
2- What are some prob causes?
3- Of course what more should I check.
I just got the car so the Helm book is order but not here yet.
So your help is much welcomed.

It may be a simple fix, it may not. However, when you gas up, make sure you ALWAYS turn the cap so it clicks at least 3-4 times or more (I always do it several times). If you don't, you will get the message you're getting about the gas. This is a simple fix. Try it next time you fill up and see what happens. If that'* not it, you need to go get it checked...probably a bug in the computer.

I had to get my computer recalibrated because it was choking out my car at about 20,000 miles. The tech just told me the computers sometimes "fall out of calibration" and they need to be taken back and re-calibrated.

Hope this helps!

Later
Jason

I was sure to tighten the cap but it still does it.

My 98 Z71 did that. It was throwing an emissions light. The cap was actually bad, and had to be replaced. Cleared it right up.

OK I checked and it'* setting 2 "P0440" codes.
EVAP Emiss System MAL.
Does someone have a troubleshooting matrix on this code?