why does the check air pressure light keep coming on on 2006 Buick Rendezvous

front left tire went flat and had to be replaced. all tires are the same size and make and all have min of 36psi.

1 answer
most tire pressure sensors must be "reinitialized" and most tire stores can do that for you. these sensors are
actually transmitters that have a built in battery. the
battery will last 5 or 6 years, then you must replace the
sensor because it's a sealed unit.