: Overactive TPM

11-05-2011, 08:11 AM
The TPMs on my 550xi GT are going crazy. They always say one of the tires is low during the cooler weather we're now getting in Denver, and sometimes they claim all 4 times are low. The car has been to the shop, full upgrade of the car's software and they ensures all tires were fully inflated and no holes - and one day later again the TPMs are going off. Now with the snow, they are going off daily. After driving 10-15 minutes I can reset them and they still off for a bit but if I park in snow, they go off again when I start the car.

I never had issues w/the TPMs in my X5. Anyone else having this problem?

I plan to go back to the dealer, not sure though what they would do - replace the sensors??

11-05-2011, 01:56 PM
Tire pressure drops about 1# for every 10-degrees F in air temp. If you're parking in a heated garage and setting the pressure there, then take it outside, it could be a lot lower pressure after awhile. Now, driving raises the pressure because they heat up, but if you were marginal, it may just put it over the threshold to trigger a fault.

If you don't have one, get a good tire pressure gauge. Leave the vehicle outside for at least several hours, take the pressure, adjust to factory specs, then reset the TPMS. Reset does two things: resets the receivers to pair with the appropriate TPS in the tire, and sets the 'normal' pressure level that it then looks for changes to to trigger a fault. You should only reset them while cold after properly adjusting the pressure, or the meaning of any warning is suspect.

Also, if your daily route has a significant altitude change, that will affect the tire pressure as well. Check this article: http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=167