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My new Ascent’s TPMS goes on after driving in hot weather on the freeway. The cold PSI is 33 as reccomended. The TPMS lights up and the dash readout has the tires at 37-38. The warning light goes off after a while but then comes back. Anyone have any insight?
 

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I just got back recently from a 2500 mile road trip. My TPMS sensors came on and off randomly. Each time the pressure reflected three tires at 35 and one at 34 etc.
I took my Ascent to the dealer for its 6,000 mile service. I explained the situation to my service advisor.
He said they had to completely turn off and reboot the computer talking to the TPMS sensors.
Only in town driving since but no TPMS sensor has come in.
 

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I've had a similar issue about 6 or 7 times during the last month. Cold tire pressures at 33 to 34. After driving 10 or more miles at highway speed, the pressures are typically 36 or 37 when the tire pressure sensor light comes on. After a couple of minutes during which time it may blink on and off a time or two, it goes off and all is well. On the one occasion when I quickly hit the steering wheel button to display pressures as soon as the sensor light came on, none of the 4 tires was displaying a reading (just as it does when you first start the car). Several days may elapse between occurences of this issue.

I took it to a Subaru dealer last week and they did the reboot thing. Too early to know if it made a difference, but I have not seen the problem since then.
 

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Haven't had this issue with the Ascent, but my Lincoln does this when I switch winter/summer wheels if the tech didn't reflash the Tpms properly. Might be a simple glitch, a reflash would probably take care of it ( unless a sensor is damaged).
 

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Why can’t anything be easy?
I just got new wheels. I assumed that they transferred the tpms sensors since the old tires on the old rims were flat. I can’t physically check until I get back home in 4 days—currently on a road trip with the tpms malfunction on. There’s no indication of any of the tire pressures on the dash.
Can anyone think of any cause for the whole system not to work besides an absence of sensors? Is there something that should’ve been done with the sensors when moving from the old wheels to the new?
Thanks!
 

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Why can’t anything be easy?
I just got new wheels. I assumed that they transferred the tpms sensors since the old tires on the old rims were flat. I can’t physically check until I get back home in 4 days—currently on a road trip with the tpms malfunction on. There’s no indication of any of the tire pressures on the dash.
Can anyone think of any cause for the whole system not to work besides an absence of sensors? Is there something that should’ve been done with the sensors when moving from the old wheels to the new?
Thanks!
I believe once the sensors are remounted they register themselves to the system. A quick stop at the dealer should resolve your issue. I would not worry about it since the only real benefit to them is that they will tell you if one tire has dropped a significant amount of pressure. Check with the dealer when you get a chance but do not fret as long as you regularly check your tire pressure (this should be done regardless of the system).
 

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Follow up to my TPMS not working:

They read each of the sensors individually and found the right front not transmitting. After unmounting it and doing whatever magic a tire shop does, I drove away with everything working normally. Apparently if one sensor isn’t transmitting none of the others will display pressures.
 

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One more tpms issue.
A few weeks I had a tpms light and one of the tires read several psi low. I planned to pull off at the next exit and check it but the light went away and it started reading normally so I checked it when I got home and pressure was normal.
Today I’m driving and after about 10 miles the tpms light came back. There was one tire reading 2psi lower than the others (same one) but still well within spec. After about 5 miles the light went away and pressure read normal again. Then a few miles later it came back on. The pic below is the dash the 2nd time it came on today.
Any other explanation or suggestions other than take it to the dealer to reboot or whatever?
Vehicle Car Speedometer Gauge Measuring instrument
 

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One more tpms issue.
A few weeks I had a tpms light and one of the tires read several psi low. I planned to pull off at the next exit and check it but the light went away and it started reading normally so I checked it when I got home and pressure was normal.
Today I’m driving and after about 10 miles the tpms light came back. There was one tire reading 2psi lower than the others (same one) but still well within spec. After about 5 miles the light went away and pressure read normal again. Then a few miles later it came back on. The pic below is the dash the 2nd time it came on today.
Any other explanation or suggestions other than take it to the dealer to reboot or whatever?
If you turn off LKA the larger TPMS screen will highlight the offending wheel. Maybe that will help.
 
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Driving to the UP and back last week was been my first trip with lengthy highway miles. I had the TPMS light start flashing 5 times on the trip. Each time the pressure display showed all four tires reading properly between 34 and 37 PSI as verified with a handheld gauge at gas stops. After 5-10 minutes, the warning would go away. The issue only happened on the interstate above 75 MPH. Once I cleared the bridge and was on secondary roads with a 65 MPH limit, the issue stopped until I was on my way back home on I-75 again. The dealer has it right now, so we will see if they find anything.
 

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@rxcrider please let us know what the dealer says.
It sounds like your issue is similar to mine. Each time the warning in the pic I posted above came in I was traveling >70mph. I'm going to have to drive it some more to see if it'll come in after a certain distance at a lower speed or just at the higher speed. I've been driving my beater to/from work the last few days now that it's running again. I noticed the tmps issue on my Ascent while the beater was broken.
Dang - you have some high pressure. Stock Falkens?
Take it to the dealer for the weird TPMS issue. Their TPMS gun tool will instantly identify the bad sensor.
I keep the pressure a little higher due to the 245/65r17 Falken Wildpeake A/T Trail tires having a much bigger sidewall so 38-39# when warm is what I expect. I'm not certain the tool would detect the problem right away because the Ascent seems to read the sensor for a while then stops. The warning usually clears when I turn the engine off and back on. Hopefully there may be some stored codes the dealer can read. I'm gonna put her in the shop for a couple of the 30K maintenance items soon.
If you turn off LKA the larger TPMS screen will highlight the offending wheel. Maybe that will help.
I'll try that. I remember someone writing about that recently and it completely slipped my mind!
 

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The dealer said there was a code stored of some sort, but that it didn't pinpoint a failed part. They cleared / reset the TPMS system and are waiting to see if it will fail again. Sounds like I need to go back to the UP for some more winter fat biking.
 

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Not always I guess. And I noticed that when I start driving the little tpms screen when ACC or LKA are enabled also shows orange tires until the system picks them up
Yes, I saw the orange tires at the beginning too, the manual says it is supposed to also highlight the tire causing the alert. Maybe because none your your tires are low on air your alert is for some other reason, not air pressure. It's obviously reading them all.

Weird!
 
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This has been bugging me since around the beginning of the year so I finally got a little more data. Here’s the scenario:

(tire pressures will be fl/fr/rl/rr as displayed)

At the beginning of the drive with tpms light on from previous drive, the sensors pick up 35/35/35/35 after reaching 25-30mph and the tpms light goes away

almost immediately I get on the interstate and drive ~70mph, tires start warming up but sensors display 36/34/36/36

about 10mi later, traveling 65-70 the entire time, sensors display 37/34/37/36, then when the rr finally displays 37 the tpms light comes on again.

the light stayed on the entire time I’m on the highway. Then I exit and slow to about 40mph on the offramp. Now the sensors display a nice warm 38/38/38/38 but the light stays on for the next minute or so until I came to a stop then it went out and stayed out the rest of the trip, which was all side roads.

In summary, the tpms light appeared to come on when there was a differential of 3psi between the tires and the tire hadn’t gone up at all while driving (actually went down 1psi).

So finally the actual questions:
is a 3psi difference one of the things that causes the tpms light?
and why would a tpms sensor not work properly only when at high speed?

apologies in advance for the lack of capitalization. It’s my phone’s fault!
 
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