Our crossfire had the same issue. Tire pressure sensor would come on and go off with no noticable patern.

Took 2 trips to dealership (techs said they did not have the right codes to read the sensors the first time and had to get them from Chrystler).

On the 2nd trip they were able to re-calibrate the tire pressure sensors. No more problems. Only took about 30 minutes (probably only took the tech 5 minutes).