My TPM won't reset.
 

It's worked many times before in the past. We had a slight decrease in temperature (about 15 degrees) and the car was parked for about four hours on a slope. The TPM came on last night indicating a low left rear tire. I refilled both rear tires to about 30 psi which is roughly where the fronts were. But no action by me on the turn stalk or the display (this is an 08MCS with Nav) will enable me to reset the TPM. I've driven around some, turned the car on and off. I don't know what else to do!

I had the same situation. I found the "low" tire was at32 @psi. I did all tires to 36, but the light stayed on. Mine reset after about 10 miles of driving; just about when I decided I had a TPM problem. Maybe yours will also.

Things to be aware of with the TPMS system.

a. they only work down to about 27 LBS. Be sure your gauge is accurate. I've tried running 28 in the rears and it seems a deep shadow will drop the pressure far enough to trigger a fault. Too close to the minimum pressure will cause problems.

b. it takes a certain speed to get the sensors to report. I can say from experience it takes a good 1/2 mile at 30 before it will clear.

Hope this helps.

Thankfully, it did reset later in the day after some more driving. Thanks everyone.

I'm curious on why you are running your pressures so low, I have a Clubman, but my reccomended pressure is 38psi.

That's just where they happened to be after a recent service visit. That said, I wish I hadn't ordered the sport suspension, as the ride at 38 psi is too harsh to suit me.