I keep getting a "Service Tire Pressure Monitor" message on my dash and it is annoying. I took it to the dealer once and they said it was not reset when the tires were rotated. i think they are full of $hit because it did it again yesterday. Is this a problem that should be fixed under warranty should I just take it to another dealer?

I think it's just a faulty sensor but they didn't want to replace it.

 

When you get the error, cycle through the tire pressures. One or more of them will show -- instead of a number. Document that in a photo (I used my cell phone) and show it to the service advisor. They should just replace the affected sensor(s) under warranty.

 

It is always the RF sensor, I will try and get a photo. Do I need the photo or will is show up on the computer as an error?

 

I don't know if it even stores it. By the time I went to the dealer, the sensor was always working properly. With the photo evidence, they replaced em no problem (this happened on 2 separate occasions and I have had 3 of the original 4 sensors replaced).

 

Thanks, I will be sure to snap a pic next time.

 

It fixes itself when you turn the key off, then back on. In my instance it is almost always the RR, no matter which wheel is in that position. It is covered in the Owner's Manual, so good luck getting GM to worry about it.
Almost every time mine does it I am near the same spot of road (near Quantico MCB & FBI training complex) I suspect some RF interference emanating from either or both sources, I also have a laptop computer set up in the front passenger area which might lead the RR to be blocked enough that extra RF interferes. The receiver for the TPMS is in that bump on the headliner above the rearview. The TPMS works on RFID technology.
As long as the msg is "svc tire pressure monitor", it is just a nag, you'll get a real warning when you've got a flat. I have exhausted my expertise now.