Cold ruins Lexus TPMS Sensor

[Scout1]

I parked my new (to me) 2015 Lexus ES350 during the recent series of snow storms in Seattle. Went to drive it today and LF tire was completely flat and wouldn't let me put air in it. The valve stem seemed to be doing something strange, not letting the button push in all the way, but after several unsuccessful tries to inflate the tire, I took it off and down to Discount Tire. They didn't find any leaks but did say the TPMS sensor was broken on the inside. They've ordered a new one so I'm back in business with just a rubber stem for now. Silly me, I forgot to ask to see the broken sensor...

I guess some ice must have made the stem crack because for sure it flattened the tire. But I'm not seeing why I couldn't put air in... It's been above freezing for several days now so I doubt there could still be ice blocking the stem. Although there still was snow on the ground around the vehicle when I started it up this morning. By the way, I added pressure to the other three tires so I don't think my air-chuck is faulty.

Anybody know what might have caused this? I'm struggling to understand how water could get into the tire to break the TPMS sensor from the inside...

 

[khittner]

Compressed air invariably includes some amount of water vapor. Before filling your tires from a hose, it's good practice to push the center button on the air chuck to vent any accumulated water from the air hose before putting the chuck onto your valve stem. Doing so will usually generate a pretty decent amount of water vapor spray that you'll be able to see and feel as wet. If you don't do this, the first few seconds of airflow into your tire will include a non-trivial amount of water vapor, which, in your case, fouled your TPMS sensor. If the PO was the last one to put air into the tires, you can blame him/her.

 

[eljefino]

I've fouled valve stems just operating them in extreme cold. Perhaps condensation from inside the tire did it. But I use warm days in winter to over-inflate my tires by 3-4 PSI then I absolutely don't touch them when it gets sub-zero.

 

[Trav]

Too bad you don't have the old one, it could have had a crack or something as simple as a bad schrader, both would be rare but it happens.
Filling tires from stations or shops is always a risk, if they don't maintain the compressor or have filters on it it can be spewing moisture into the tire and you wont see it.

 

[Scout1]

Originally Posted by khittner
Compressed air invariably includes some amount of water vapor. Before filling your tires from a hose, it's good practice to push the center button on the air chuck to vent any accumulated water from the air hose before putting the chuck onto your valve stem. Doing so will usually generate a pretty decent amount of water vapor spray that you'll be able to see and feel as wet. If you don't do this, the first few seconds of airflow into your tire will include a non-trivial amount of water vapor, which, in your case, fouled your TPMS sensor. If the PO was the last one to put air into the tires, you can blame him/her.


This makes a lot of sense to me. I'm always pretty good at checking and adding a few pounds of air as the weather changes and the Lexus was no exception. I never thought about clearing the moisture from my garage compressor/hose before I use it. And the left front tire is always the one I start with just based on where I do the air checks, so that tire likely did have some moisture in it! Guess I'll start clearing the hose from now on!

 

[Trav]

Put a separator/filter unit on that unit, sometimes you can get a steal of a deal on a Parker unit from Amazon.
I bought 4 complete units for $30 ea list is almost 300, demarpaint also picked one up. You have to scan a lot of pages.
Ebay also has a lot of NOS good names on the cheap.