Why is my tire sensor light on

Had this happen on an Optima - first thing I would do is try and reset the computer and see if it comes back. If it does, the TPMS module is dead. It won't affect the car's safety since if it's already dead it comes back. If the sensor is dead, they end up erroring out the same way either way. Don't go in with high expectations; only bother with this if you own a scan tool that can reset the TPMS system, and you are only paying for 10 minutes of your time.

If the sensor is bad, it is sometimes possible to DIY it as a lot of newer cars do it automatically or have a relearn procedure the ECU can do on its own, but some cars do not have this. For those, you need a TPMS tool that can activate OEM sensors. A lot of companies make TPMS modules, but they require their own to clone an OEM one. Outside of a handful of really cheap ones, they all can activate OEM modules or ones that are already active and ready to use. Autel has the TS501 Pro, which can activate them and also create Autel TPMS sensors from the bad ones. Other lower-cost tools are out there, but make sure they support physical OBD2 and have a relearn mode that supports any TPMS sensor from the OEM or even pre-activated clones. You will need to dismount the tire, so it's generally not DIY friendly unless you can mount and balance your own tires, or you can dismount enough of the tire to access and replace it.