My problem; I wanted to do a little grocery shopping this morning, started the car, pulled out my driveway and got 1/4 mile from my home when I noticed the TPMS indicator was on. I turned around and figured I'd put a little air in whatever tire it was that was low (4 new tires installed on this car in March). I tried to screw off the valve stem cover but it was on too tight. By this point my husband arrived and also tried to unscrew the cap - to no avail. He had to use a small wrench to turn the cap (I'd like to know why the mechanic screwed the caps on so tight in the first place!) and upon doing so, the entire valve stem came out immediately and expelled all the air from the tire.

Now the question is- can the valve stem itself be replaced or do we need to replace the whole TPMS unit in the wheel/tire? Any help/advice greatly appreciated! Thank you!

 

There are two tire pressure monitoring systems available, a base system and a premium system. The base system does not specify how many tires are low or where they are located. The premium system does so.

The Base TPM system consists of tire pressure monitoring sensors attached to each road wheel through the valve stem mounting hole, a central receiver module (WCM) and an indicator lamp.

The Premium TPM system consists of tire pressure monitoring sensors attached to each road wheel through the valve stem mounting hole, a wireless control module (WCM) three wheel sensor transponders located in three of the four wheel wells, an electronic display, and an indicator lamp.

The valve stem should be able to be replaced without having to replace the TPMS sensor, the sensor should be able to be attached to the stem as long as it wasn't damaged.

 

And I'll bet the ape that mounted the tires used his mega-torque impact wrench to tighten your lug nuts so that there was no way you were ever going to get them off with the lug-wrench in the trunk.
Memo to anyone reading this, the proper spec for tightening lug nuts is 100 ft-lbs. The only way to achieve this is with a torque wrench. Insist that they use one when tightening your lug nuts after any wheel rotation or tire mounting. Impact wrenches are for REMOVING lug nuts, not installing them.

 

Well said dcotter ! ! !