What the heck?

On my 2000 Voyager every so often the check engine light comes on and the car goes into low gear. I read it had something to do with the gas cap. So I took it off, then put it back and retighten it to the first click and the light went out after a while and the car is in the right gear. I did notice that every so often my gas cap becomes loose and then the car goes nuts. Is this really the problem? I have 100,000 miles on the car.

I think you have two separate issues.

First, when you tighten the gas cap turn it until you hear four or five clicks.

IF the rubber seal on the cap AND there is no rust on the end of the filler pipe the cap should seal properly.

Second, when the tranny drops into first or second gear it usually means it’s in the ‘limp mode’ and you need to have the tranny checked.

Have the computer scanned for codes, a loose gas cap will not cause limp mode in the transmission. Have the codes read at one of your local auto parts stores and post them here and we can go from there.

transman

Will do. I will get back to you next week. Thanks!!

Transman,
If you’re talking to me (not sure), my post did not say the loose gas cap caused the limp mode.

That’s why I said I thought their may be separate issues.

I doubt it - the OP’s post suggested that s/he drew a connection there.

transmission solenoid. See a dealer or trans shop