I've had two instances when the Volt's TPMS has flipped out and indicated that all four tires are at "--" pressure; not "zeros", but dashes. Both times were during a hurricane event and both times all four tires were properly inflated. The first time happened when I was evacuating from Hurricane Matthew and then it just happened again with Hurricane Irma. Coincidence or is there some connection with barometric fluctuations related to hurricanes?