I have one of those "lifetime" guages that reads in PSI to a 0.5 PSI accuracy. The beeper sound was weak, then today it showed an "L" instead of a pressure reading, so I removed the CR2032 battery, and put a new one in a few hours later. Now it shows "01.0" when I read something that is at least 30 PSI, and does not beep.
Does the unit need calibrating, or pitched away? Will BMW honor any sort of lifetime warranty? TIA