I recently purchased a 2011 Impala LT. The car had 20inch wheels and tires that I did not want so the dealer swapped out the wheels and tires for factory 18 wheels and tires from a 2008 Impala 50th Anniversary edition. Of course the TPMS coded with the warning light as well as the message of Tire Pressure Monitor Service. To avoid the dealer here is what I did.
Turn the ignition to run without the engine running. Press and hold the LOCK and UNLOCK buttons on the key fob at the same time. Horn will honk twice and the message relearn mode will appear. With a ball point pen I released air from the drivers side front tire (about 7-8 pounds) until the horn chirped. The air release must be continuous until the horn chirps. I then moved to the passenger front, Passenger rear and the drivers rear repeating the same air release with the ball point until the horn chirped at each tire. The horn should also chirp twice at the driver's rear tire when all positions are learned. I then turned off the ignition and then started the vehicle. Warning light and Message are gone and all 4 TPM'S are functioning in the correct position.
The key is to remove the caps prior to starting the process so you can move quickly to each tire. Also, you must follow the sequence or the process will not work. DRIVERS FRONT-PASSENGER FRONT-PASSENGER REAR-DRIVERS REAR. IN THAT ORDER and be sure the vehicle horn chirps twice at the driver's rear tire.
NO NEED TO BUY ANY EXPENSIVE TOOL FROM GM. A BALL POINT PEN and attention to the sequence. Worked perfect.