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Today I noticed my tire pressure isn't displaying. Instead of the symbol of 4 tires with the corresponding pressures, there are just dashed lines where the pressure used to read. It worked in the past, just not today when I checked. Nothing changed since last checked that I know of. Any ideas why this might happen before I add to the list of things to report at first oil change?
 

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Well I'll be...
I could'a sworn I've checked it prior to leaving the house, but I guess not. Why would Subaru do this? Wouldn't checking tire pressure before a trip be better than once on the road?
 

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Well I'll be...
I could'a sworn I've checked it prior to leaving the house, but I guess not. Why would Subaru do this? Wouldn't checking tire pressure before a trip be better than once on the road?
I think it is a bit odd too and I agree it would be useful to know if the tires are inflated before driving off.
 

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I notice my brothers Highlander (prev gen) has real time tire pressure, not requiring to drive around like our Ascent. I read the TPMS with a laptop scan tool, bc he only have the low tire pressure light indicator.

So it’s really up to Subaru how they strategize the display of the tire pressure
 

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Greetings,
It's not distance that activates the TPMS reading, it's speed. Page 342 of the 2019 manual:
"The tire pressure monitoring system will activate only when the vehicle is driven at speeds above 20 mph (32 km/h)."
 

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Greetings,
It's not distance that activates the TPMS reading, it's speed. Page 342 of the 2019 manual:
"The tire pressure monitoring system will activate only when the vehicle is driven at speeds above 20 mph (32 km/h)."
The odd thing is that it's not.

When I air down to off road on the beach, it will accurately adjust, and I don't exceed the posted 10mph or 15mph.

When I air back up at the edge of the highway, and take off at 55, it takes a couple of miles to adjust.

When I swap tire positions, it takes 20+ miles to put the data in the right position.

However the system works, the sentence in the manual is an oversimplification at best. I'd found more info on it somewhere, and am trying to find it again.

I think what it's saying is that it turns on at 20mph but then keeps working until the car is turned off. Kinda like Adaptive Cruise Control. That'd explain my beach results, since the car is left running.
 

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I think what it's saying is that it turns on at 20mph but then keeps working until the car is turned off. Kinda like Adaptive Cruise Control. That'd explain my beach results, since the car is left running.
Oh sure- the key word is "activate." It doesn't stop working when you slow down and stop.

You say it sometimes takes a while to "adjust." But it is showing something, right? I think the 20 mph threshold is to go from no reading to some reading. I suppose whether or not the readings are correct is a different matter.

Anyway, it's a simple experiment. Just start the car and accelerate past 20 mph to see if the TPMS goes from dashes to numbers. I've watched it do so when I hit 20 mph in far less than a mile of distance.
 

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Right, but I've switched tires and watched it not notice for 50 miles of highway driving.
 

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Sounds like the same engineers that designed the automatic parking brake engagement and automatic RAB disabling circuits had a say in the TPMS, also.
 
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