With my 2004 impala the speedometer will work fine after driving for about 20 minutes. Then it will go way up to 110 and back down to 60 then stick at like 70 until I pull over and turn the key off and on enough for it to go back to zero. Sometimes this will fix it for a while and sometimes it won't. Any ideas?

The problem with your speedometer may be a bad electronic cluster in your gauges. Had a similar problem with the oil and temp levels. If under warrenty, take it to the dealer and should be covered for the replacement part. Part may be order directly from Chevrolet. If not covered, parts and labor will run you around 300.

If you're not picky about which display you get (i.e base model w/no tach) you can get an instrument cluster for ~$50 off ebay


search "impala cluster"

let me know what you did to fix yours. My father in laws 2004 is doing the exact same thing. Out of warranty of course and GM won't do a thing, and they wonder why people are buying foreign.

These cluster problems are very common. Email a guy named BBEngineer@comcast.net. He rebuilds and modifies clusters, and can get you one fairly cheap. By the way, here is how to get your cluster out:http://impalahq.naioa.com/ Look under "How To:" and then "How to remove the instrument cluster trim plate"
If you buy a cluster off ebay, be aware that it will not display the correct mileage. Mileage is stored on the cluster itself, and the cluster must be taken apart to reprogram it. Also, just because a cluster will fit in your car does not mean it will work right. Some years and models will only work with certain other years and models.

We had the same problem with our 2004 not only the speedometer but all the gages went wild. I was able to get it repaired under a "Good Will Warranty repair" the actual cost would have been $562 for a exchange cluster. Dealer tells me problem is very common with the trucks but not as bad with the cars.
I figure I got lucky getting it fixed this way. Good luck:thumbsup: