Tire Pressure acts strange FIXED

2 weeks back, when i started my car after shopping, it showed Front Left tire yellow "pressure low, drive and brake safely". i drove home, waited the tires to cool down and checked with gauge - all showed around 38 psi. so i started the car and resetted TPMS. Guess what, warning went away.

i read in another thread that there is a threshold for the TPMS indicator to turn yellow, and it is 25 psi. i would imagine that the tire pressure go down below that once the tires cooled down. Normally, warnings show up during startup, but goes away once the tires warm up. in my case just the opposite has happened.

same thing happened the next time i took my car. after driving 10-15 mins (i.e tires warm up), warning in front left. once back at home and tire cool down and TPMS reset, it goes away. anyways, i went ahead and filled more air into the problem tire and ever since no warning occurred even after driving quite a lot.

last week i coded for TPMS pressure display. it shows the same thing! the problem tire shows 27 at cold start, goes up to 28.3 and then after 15 mins driving, even though tire temperature keeps going up, pressure goes down to 25.5.
no warnings yet, confirming the 25 psi threshold for yellow. all other tires behave normally. ie. 37 psi at start increases to 40 along with the temperature rise.

is the tire flat??

Sounds like you have a bad sensor.

Did you also check the tire pressure with tire pressure guage?

Side note, I may have seen you on I-90W between E 55th and E 72th street exit on Sunday evening

Originally Posted by Silververtu

Did you also check the tire pressure with tire pressure guage?

Side note, I may have seen you on I-90W between E 55th and E 72th street exit on Sunday evening

Heyy.. good to see a fellow fester from CLE!!
F10's are very few in number in here, I must say. My eyes light up even when i see a BMW!

Yes, i checked the pressure with my guage, it showed all four at 37-39.
im gonna buy two more and measure to confirm it. (thats what TJ does! )

I'm also having a similar issue. The manual says that my particular tires should be at 35psi.

I had the sensor come on last night, and checked all four tires this morning. They all read between 33 and 35 psi. (this is using the previously recommended Amazon digital gauge.) I filled them all a little, so they're now around 37ish and reset the system. So far so good.

This is the second time this has happened, in about 2 months. Bad sensor??

I recommend this gauge. It works quite well for me - http://www.amazon.com/Accu-gage-Tire...pr_product_top

i check my tires regulary,with a guage.
as soon a the weather got cool here, tire alerts came on at startup.

when i checked them they were all down around 10 pounds each.
i have never seen tires drop that much pressure before.

this is the first time ive ever had runflats and dont know of they lose more air or lose it more quickly then traditional tires.
the low profile tires make it more difficult to see the loss. when driving i didnt feel the loss,because the loss was gradual.

Glad to report that the issue has been fixed. As X Men had spontaneously diagnosed, it was indeed the sensor system at fault. replaced that and now my TPMS shows very similar pressure to my guage.