[Mazen328]

Hi,

My 2010 e90 has TPMS. I recently installed my spare tire to fix my rear rim and inflated it to the correct pressure. The spare tire does not have a sensor. I was expecting an error from the TPMS because there was one sensor missing but it didn't happen. Also in the Idrive screen, the 4 tires are in green color indicating the pressure is correct in all 4 wheels. Any clue why the system did not complain about the missing sensor?

Regards

[jeddo45]

1 of 3 things: 1. Your spare has TPMS. 2. You stuck your old tire in the trunk and it's still reading it's pressure. 3. Your TPMS is faulty.

Just guessing here...

[Mazen328]

The spare doesn't have a sensor and the tire is not in the trunk. The TPMS was faulty, I installed 4 new sensors and it worked.

[delmarco]

Originally Posted by Mazen328

The spare doesn't have a sensor and the tire is not in the trunk. The TPMS was faulty, I installed 4 new sensors and it worked.

Curious. My suggestion is the TPMS system is pre-set up for the event a tire goes flat and a non-TPMS spare is put on. Not seeing a single TPMS but still seeing three working TPMS sensors then the system assumes a spare is being used since the car is still driving.

However that hypothesis makes no sense since our cars come with run flats and the TPMS programmers would not have thought that far ahead.

[Mashman]

I would guess that your car is setup with FTM-'Flat Tire Monitor' and not TPMS-'Tire Pressure Monitor System'. What does it say in iDrive?

TPMS uses sensors in the tires, to monitor actual pressure. FTM uses the DSC to monitor the roundness of the tire. They both are designed to notify the driver when a tire goes flat.

Even if the car came with TPMS, it's possible to code it to use FTM instead. That way you never need to worry about the sensors when you change tires.