TPMS Light Flashing-Why?

For the past month or so, whenever my trip timer reaches 21 minutes, my TPMS light starts to flash. Turning the car off and then back on stops the light from flashing but 21 minutes later, its flashing again. My snow tires are inflated/aligned. Nothing seems different before/after the flashing. Anyone know what could be causing this? 9/10 times its always 21 minutes, I've seen it do it at 26min too.

I didn't realize that TPMS was available in 05s.

 

Our two Subarus both have it, and the systems behave differently in the two model years we have. So it doesn't surprise me that your system is different yet again -- although it sounds more like the system in the 07 OB, which doesn't start warning of a low tire (or a malfunction or whatever) for some significant interval of driving (but I've never timed it).

 

You mentioned "snow tires." If they're on after-market wheels that don't have sensors, or if they have sensors and you didn't get the system reprogrammed at a Subaru dealership, that's the problem.

 

If you're using your OEM Subaru wheels, which, presumably, have the Subaru sensors in them, I expect that the tire swap resulted in a broken sensor. Stuff happens. HPH

I'm using my snow tires (Blizzaks) with my stock 17s, which were mounted by Flatirons Subaru (Boulder). So the flashing TPMS light means that I got a bad tire sensor? Nothing worse? Any reason why at 21minutes?

i had a flashing TPMS light on my wife's Outback...turned out one of the tires was OVER pressure/filled. We were up at mammoth snowbording, Solid TPMS light comes on, so I have fill the tires, plus i assumed a drop in PSI coming from SoCaL up to the snow & colder weather...so topped off th tires and all was well that weekend.

 

on the drive home/back to socal...naturally the temperature picked up thus creating even more PSI in the tire...so ultimately back at home the tire was OVER filled. Let some air out, reverified the PSI reading with a tire guage...all was well. Drove around for a bit, solid TPMS light turned its self off...

 

But yah, on the drive home, we'd break for gas or food, shut the car off...get back on the road and bam...flashing TPMS light back on after a few minutes of driving.

 

hope that helps

Flashing TPMS usually means there is a fault with the sensor. If the sense is around 4-5 years old the battery could be dying.

SnoDork- That makes perfect sense because...9/10 times it comes on is when I am going to work up in the mountains at over 9,000ft, a 4k increase from where I started. I just drove down to denver which is a loss in altitude (not much) and it didnt go on till 40min...hmmmm

21 minutes sounds about like the timing on our 07, although I've never checked it on a stopwatch. It seems to wait that long to signal anything (either a low tire or a fault -- we've had both).

 

The 08 is immediate, however, at least for faults. And it's not the sensors by themselves, as both OEM and Tirerack sensors have the delay in the 07. The Tirerack sensors are immediate on the 08.

 

I don't have a clue. HPH

yeah flashing means that the system isnt reading the sensors.