Recognizing how the system works is the first thing, but TPMS appears to be a problem prone technology. My tires would always read 2-3 lbs lower than actual on the dash display. Perfectly normal. At 12,000 mi. my left rear, properly inflated, began to read low (as little as 13lb) when cold, would increase rapidly while driving ( to as high as 60 lb.). I suspected a bad sending unit, but now the left front (inflated to 29 lb this AM) is showing -4 lb., gauge shows 31. Could be another sending unit, or worse, the recieving unit. My nearest dealer is four hours away, so I am waiting until I can take a 2-3 day vacation to see about repair. To be fair the TPMS has properly alerted me to a low or flat tire on two occasions, so it has real value.