We'll, this is special

[xela]

I had a low-tire light this morning, so went to the gas station. Brought all the tires up to pressure, got in to drive away, & it feels like my brake is set. It's not. Get out to look. My L front tire is now visibly flat. As is my R rear.

The mechanic - and boy am I glad I went to an old-school gas station for air this morning - just came in & told me my pressure sensors are broken.

"And that makes my tires lose pressure? How does that work?"

Turns out the pressure sensors are built into the valve stems. And by inflating them this icy morning, I caused two of them to freeze. Or so they tell me.

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Comments

[siderea]

Technology makes everything better!

[jered]

Fascinating; I always thought they were attached to the inside of the rim, but googling "tire pressure sensor" shows that your mechanic is correct! Or rather, the original ones were on the rims but they've migrated to the inside of the stem.

I'm somewhat surprised they could have the failure mode you suggest, though It seems more likely that you've just gotten ice crystals in the valve stem, independent of the TPMS component.

[jered]

Yeah, Brian confirms my theory. You can get ice crystals in your valve stem; you should warm it up with your hand before inflating. The pressure sensor isn't in the air path so it can't cause the problem you describe. So, mechanic was half right...