[Dave at Pelican Parts]

There are two different kinds of TPMS used on MINIs.

One type uses the ABS sensor rings on the wheels to compare wheel speeds. The idea is that if one wheel is consistently spinning faster than the others, then it must have a smaller diameter and therefore must be underinflated. Presumably the software will ignore differences that are small enough, and will compare data over some period of time, but I don't know what those specifics are.

The other type uses four sensors to directly measure pressure. These are attached to the valve stems, on end of the stem that is inside the tire. These have small pressure sensors and a little low-powered radio transmitter (probably something like Bluetooth but even lower-powered and one-way) that tell the computers in the car when the pressures change. I don't think they send an absolute pressure reading, but I'm not sure about that. These sensors have batteries built into them to power them, and the batteries do eventually die. As far as I know, the valve stem and sensor has to be replaced when the battery dies.

I do not know which yours would have; I know that for my 2012 all of the US-market MINIs had the direct-sensor type. On my car, I get notified which tire has low pressure detected; the readout in the tach shows a pointer on each corner that has a low tire.

I think your best course of action at this point is to find a dealer or an independent shop that has the equipment to check what the car is seeing. Remember that generic code readers will only find some of the information you need; the shop needs the actual BMW- or MINI-specific reader.

--DD