Originally Posted by ZH SRT6

The sensor battery will be too weak to send a signal all the way to the car's receiver up by the mirror LONG before it comtpletely dies. Mine still transmitted to the handheld TPMS tool at least four months after the warning light came on (although two wanted to be triggered by the magnet, not the TPMS tool LF radio trigger signal).

Even after the battery might be COMPLETELY dead - the factory sensors, at least, have their fixed ID number printed on a label on their body. So a tire shop COULD use that printed code to clone a new sensor. But probably have never done it that way before, so will believe it is impossible. The way they have done it is by walking around the car, recording the old IDs into the TPMS tool, then using the tool to clone replacement sensors.

I have been asking Bartec, makers of the standard TPMS tools (also sold under several other brand names) how this cloning using a WRITTEN sensor ID can be done with their tools, don't have a satisfying answer yet. But they confirmed it CAN be done.