One of my tires started showing 5 PSI below the rest, even when the pressure is the same in all 4 tires. I took the car to Costco, thinking they may be responsible for the TPMS sensor when they changed my tires. It turns out the sensor is part of the wheel set.

Taking the car to Lexus next week t have them diagnose it.

Anyone else have this issue?

 

I may have thought a weak battery, but since you have a 2012 that shouldn't be the problem. I am curious what the dealer says.

 

Have you checked the pressure in the spare?

 

I agree with Jim the spare threw me for curve when my sensor light came on. Forgot all about the spare.

 

Update: Lexus says they initialized the system and found no trouble. To be continued...

 

You were right. The spare was the culprit!. In a 2012 LS, the tire pressures are shown in a strange order, that I diagnosed with the help of my Lexus service adviser. Here is the order from top:

Spare
Right Rear
Left Rear
Left Front
Right Front

This is very odd. I would have expected the spare to be the last, and starting on either Front Left or Front Right. Oh well.

 

On your car the tire pressures are displayed in no particular order other than the order that the sensor IDs were loaded into the car's system. If the tire that is displayed at position 1 on your car (the one that you have identified as "Spare") were moved to any other location on the car, it would still be displayed at position 1.

 

Doooh!

And as to

I believe you can change this next time you rotate your tires.

 

Thanks for clarifying. It is a mystery why Lexus would not identify each wheel by location. I understand newer models display this information.

 

No kidding. In case I forget the locations, I saved the sequence in the phonebook in our nav unit

 

That's a good idea. I've been keeping on a post-it note in the center console.

 

Yeah, everytime I want to top off my pressures I find myself rechecking the sequence

 

I am running into an issue with my TPMS. I had purchased a set of 20" wheels for my LS460L. I had noted that CJTTY had posted (a while ago):
"OEM TPMS SENSOR INFO:

The TPMS OEM part # that I can verify works because I bought a set is part # PMV-107J and Amazon has a set of 4 with rebuild kits for $95...a fraction of dealer prices for same part!! Don't pay full price!!! Simply search that part number on Amazon or EBay..cheaper on Amazon as of this post..you're welcome"

based off of this I bought a set of TPMS off of ebay, and had them installed with my new tires/wheels on Thursday. everything was fine Thursday night but, today as I was driving I got the "check TPMS system" message on the dash. at first i was wondering if I should bring it back to Tires Plus (where I had the install done), thinking that maybe they did something wrong. Or maybe there is something wrong with the TPMS that I purchased off Ebay. However, I have discovered on CL one thread where there is discussion about TPMS needing to be reprogrammed if using multiple sets. And now in this thread, it sounds like maybe the issue could be the simply the spare tire?

So, i'm wondering:
a) if maybe I am just better off taking my 18"s back to the shop, and have them swap out the TPMS on the 18"s for the TPMS that are currently in the 20"s? Or,

b) is it pointless to have two sets of TPMS, and I should just sell mine?

c) the issue has nothing to do with my sensors, and is just a matter of tire pressure not being accurate all the way around the 4 tires and the spare.

I'm just trying to narrow down what could be the cause of this. I'd appreciate whatever suggestions that you can offer.

 

Now that I know my locations, I will make sure to update the sequence at the next tire rotation. Post it it is!