I would first make sure that all tires including spare, are adjusted to the required pressure, as indicated on the decal on the drivers door or door post. As a 1-2 lbs drop, can trigger the light, use a digital gauge, keeping in mind that if it checks normal at a gas station, that it will likely be 1-2 lbs lower when cold ie, undriven.
Each sensor is basically a battery operated pressure transmitter. The internal battery on each sensor is sealed and therefore, non serviceable. These watch type batteries weaken and often need replacement after 4-6 years of use. Expensive proposition when you need to replace all 4 or 5 if equipped on the spare as well.
Most tire shops and all dealers have a radio signal tester, that will measure signal strength. That should be a no charge service to test as it takes just seconds, to perform.
No sensors going out is one reason I really like VW's system, it measures the tires rolling circumference using ABS sensors and when pressure drops it notices a difference and throws the light. All you do to reset it is set the tire pressures cold and push a button and it relearns the parameters.
The sensors on my old impala were always getting confused where they were when you swapped tires, and then went out altogether so the light was always on and the office didn't want to spring the $ for new ones. Useless!
OK, Im not being a smart ass here, its a serious comment.
Pull out your Owners manual and read it. You will find some really good info in there.
Matter of fact, Homework for everyone is to pull out their owners manual and read through it.
There is a reason for that manual.............
Things like the TPMS system, ABS system , traction control systems etc, will list operation / symptom charts to help you determine what is a problem
or what is a normal corrective response from these management controls.
Yes we do get customers coming in thinking that when [ Lets use this for an example ] a corrective function of one of these systems activate,
That they have a problem, not realizing the car "Did what it was supposed to do".
So read your Owners manual, and we will have a Test on Monday.
High score gets a Case of Beer.
Low score has to dump the Oil drain buckets !