I had (have) this problem also. I had utilized the battery disconnect for a few months while I was away and when I returned and started the car, the TPMS light was on. My research makes me think the calibration was lost, and there is an easy to find procedure to reset that...using the TPMS button on the lower left dash. Unfortunately that hasn't worked for me, and I have tried more times than I care to count. I have a Launch computer that does a fairly decent job for most things, but it won't communicate with the TPMS for some reason so no luck with resetting it there either. My next stop is a pretty good local tire shop..They have sensors with the correct frequency and some kind of computer to read them and confirm they are working. My other thought was a TPMS battery may be dead. Anyway, still trying to figure this out myself, if I come up with a solution I will reach out...Good luck.
