When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
The TPMS on my 2007 ES lit a few times over the years, once when all tires were properly inflated. After some research, I checked the spare and it was indeed low. It took driving around, and a stop where I turned off the vehicle, went into a store, and then restarted the car before the light went off.
I'm pretty sure I read in the manual for my new 2015 RX that the TPMS sensors cover all 5 tires, including the spare. I will have to check the books again when I go out to the car. I have read so much the last few weeks that I'm not 100% sure without checking!