Sensor Training (Reset Procedure)
You will need a special tool - Tire Pressure Sensor Magnet - to complete this procedure.
Turn the ignition switch from the OFF position to the RUN position three times, ending in the RUN position. Do not wait more than one minute between each key cycle.
The horn will sound once and the TPMS indicator will flash if train mode has been entered successfully. If equipped, the message center displays "TRAIN LF TIRE", place the magnet on the valve stem of the LF tire pressure sensor. The horn will sound briefly to indicate that the tire pressure sensor has been recognized by the TPMS module.
Within two minutes after the horn sounds, place the magnet on the valve stem of the RF tire pressure sensor. NOTE: If the VSM (TPMS module integral to VSM) does not recognize any one of the four tire pressure sensors during the tire training procedure, the horn will sound twice and the message center (if equipped) will display "TIRE NOT TRAINED REPEAT" and the procedure must be repeated.
Repeat Step 7 for the RR and LR tires. When the tire training procedure is complete, the horn will sound once and the message center (if equipped) will display "TIRE TRAINING MODE COMPLETE".
You can pick one up at any local parts store. They aren't that expensive, only a few bucks.
First off- the dealer never gives a straight answer, they want you to spend TONS of money with them. If they told you it is osmething you could do yourself, they'd be broke! As for the new tires being installed- If the techs that did the tire swap were not careful, they very well could have damaged a sensor. However, I would first reset the sensors and see if that cures the problem. If not, I would suspect the installation of the tires did in fact damage a sensor.