TPMS issues

What goes wrong with the factory TPMS wheel sensors? One on my '08 Silverado is reading very erratic,bouncing all over the place high and low.What goes wrong with these things anyway? I know they're readily available online but I'm just curious what it is that causes these to go bad and not read a constant pressure.

Batteries get weak, for one.

If your original ones from 2008 are still working consider that a miracle. I've heard that the usual battery life of TPMS sensors is 7 years.

I wondered if it might be battery related.I take it that it isn't a serviceable item and requires a swap?

Good to know,thanks guys.

Check it for fault codes also.