Tyre Change & Relearn
Every time a TPMS sensor is replaced (because it is broken, the battery is low or winter tyres are fitted to the vehicle), it has to be activated and the vehicle ECU has to be reprogrammed with the unique ID of each sensor. Otherwise it would not recognize the new sensors and indicates a TPMS failure. The programming usually involves certain relearn procedures that differ from car to car and can be fairly lengthy.
Especially during the winter tyre season, when not only 1 but 4 tyres, and hence 4 sensors, per car need to be replaced, the amount of work is considerable.
A good TPMS tool, such as the Bartec TECH400SDE, can not only activate all TPMS sensors but can also relearn vehicle ECUs via OBDII connection or at least shows the procedures on the display so that they do not need to be looked up. This saves the technician a lot of time and enables him to process more cars.