I'm leaving work and I see the low tire pressure warning pop up.. Urg... So I stop at a gas station and put air in.. As I take the cap off my right front valve stem I see a small black rubber ring on the inside of stem.
I filled up all tires with some airyet I don't have a tire pressure gauge. But low pressure warning is still going off..

my big guestion is what is the ring?I will buy a gauge later and find out if my tires are "low" which I don't believe... Could the ring be related to the TPMS?

 

That was prob just a gasket from the valve cap

 

that's another posibility that I was thinking too sixsix.. Probably right.

 

Don't forget to check the air pressure in your spare too.

 

It's always a good idea to check your spare, but the spare does not have a sensor.

 

And that is why Costco puts nitrogen into the replacement tires they sell.