My tire shop changed two TPMS sensors and did not have to reprogram the computer. Well, they managed to mess up the location of all the sensors and two or three of them read blank or 148psi. It wasn't until I took a pause and did it again in the morning exactly as the instructions stated that it worked out for me. There were two other GM vehicles in the shop at the time, being driven in and worked on, and it is quite possible that their signals from their remotes interfered with the operation; GM talks about this in a TSB.