I have a lease on a 2008 MCSC that I keep garaged and haven't done too much motoring with since I got it a few months ago (the unfortunate result of an emergency surgery it took me awhile to recover from). I recently began taking the car out again intermittently (since my back has healed enough for me to drive again) and on my second trip out in the car, which followed a week in which it recieved no use, the TPM light turned on. I took a quick look at the tires, and all four of them appeared to be perfectly fine. The next day, when I took the car out again, the light was accompanied by the audio signal saying I have a flat.

The manual says under these conditions, I should reset the TPM system, but the '08 MCSC doesn't appear to have the reset button shown in the manual. I tried calling my dealer's service department this afternoon, and nobody answered--apparently they all got the long weekend off. Can anyone here advise me on what to do next to diagnose the problem? (ie, what should I do to find out whether or not I have an actual tire problem, and what should I do to reset the TPM system so that I can relax and not freak out about this if if nothing is actually wrong). Thanks in advance...

 

Sorry for the obvious, but you did check the air pressure after it sat a couple months right? If it's got runflats, they can have zero pressure and look normal to the eye.

If you have the Nav option, the reset is in the TPM section of the settings. I'm not sure where it is for non-Nav equipped cars. Some one else should chime in here shortly.

 

I don't have the nav system, just the idiot light for my TPM. Anyway, following your advice (why I didn't do so off the bat, I have no idea), I picked up a digital-LED tire pressure gauge at Home Depot. It would seem that all four tires are about 10-12psi shy of the 35psi recommended in the sercive manual--they all read between 22.3 and 24.7psi. I suppose the cumulative low pressure may be enough to persuade the car that there's a flat. I'm going to swing by a gas station later and top off all four tires to see if that makes a difference (which I expect it will).

 

I'm not sure where the TPM button is in the 08, but in my 06, the reset button for the TPM is by the emergency break. (I think it's on the right side). To reset the TPM, put your key in the ignition and wait for the first click, then hit the TPM button and turn the motor on, the light should go off.