After a week in the airport parking lot, my SC430 alerted me upon return that the tire pressure was low. I checked all the tires the following day and found that the pressure was around 30 psi for all 4 tires. I increased the air pressure up to 33 and the light turned off. Very sensitive. A cold front went thru the area and that probably reduced the tire pressure. All is well.
Just 2 weeks later and the light came on again. Again, cold front came thru over the weekend and the car was sitting outside. I started the car up on a cold Monday morning and, bingo, the light is on. I have not checked the pressure in the tires again, but will take a look later in the week. Just a major design flaw. These TPMS' are not what I expected.
USER ERROR! Actually, the tire pressure was low in one of the tires. It was only a few psi below normal, but did require me to put some air in it. The roller coaster ride continues.