Tire Pressure Monitor warning

The cold has probably dropped the tire pressure below the warning point. Go to any gas station and add some air in the tires. There is a sticker on the driver's door jam that specifies the recommended pressure. These days tires only look low when they are really, really low. If the light comes ON, the pressure is at least 20% lower than it should be.

 

What are the tire air pressures? Go measure them. We can't tell much of anything without those?

My 2012 Liftback has had a few false alerts in two different wheel sets (summer and winter), with sensor batteries too young to likely be failing. I don't yet have a solution.

 

Where are you? If you are driving on ice, sometimes the slippage will trigger an alarm.
X

 

happy new year!

 

Yes probably.

And finding a place that is open New Years might not be that hard.
Auto parts stores like Auto Zone likely have limited hours.
Maybe WalMart auto service too.

You REALLY should have your own tire gauge. Really.
You can get a decent one for around $5.

 

This is a good basic one, the simple pencil style:

Milton Industries S-920 Tire Gage

Ideally you should check the pressures when the tires are cold, say car driven less than a mile. In practice, if you're checking them at a gas station after prolonged driving, air the tires up to 4~5 pounds over what you're aiming for, then recheck later when the car's sat for multiple hours, ideally overnight.

The specified tire pressures are in the door jamb, on a sticker. Toyota seems to typically show slightly higher pressures for the front, at least on the Prius. I set a uniform pressure, on all four, a few pounds higher. Works for me: I know they'll be ok for a while, and when rotating tires I don't have to raise some, lower some.

 

I would not trust that analysis.

But if it is true, you may need to reset the monitoring system.
That needs to be done after each tire rotation.......because the "normal" pressure is different front and rear.
How to do that is in your owners manual.

 

I'm not sure about that, I mean: the Prius system is not telling you which tire location is the one that's low. The one reason I can see to do the reset would be if you're doing a significant change, and really want the system to be aware of it. Considering it apparently takes a 25% drop below the "set" pressure to set off the warning, I've never bothered to reset ours, after one initial reset, maybe 7 years back.

FWIW, I set all my tires to the same pressure, a few pounds higher than the spec for front, keeps it simple when rotating the tires.

 

IIRC, the difference is about 4 PSI. That alone will not trigger an alarm but it's well on the way.
This is assuming, of course, that the "tire technician" actually adjusts the pressures front and rear after the rotation.
The "book" says to do the recalibration.

 

Huh, you're right:



And I can see why: even though there's only one dash indicator, the system IS tracking the pressures of four distinct ID sensors.

Doing my own rotations, just playing around with front vs rear pressures got old, early on, so I opted to set them all the same pressure. I've not noticed any difference in the feel/handling; it seems somewhat overkill. With our 17's it's actually a whole one pound difference, front/rear lol.

I might have actually done the equal pressure thing after the last TPMS reset (actually the one and only). It apparently takes a 25% drop for them to light the warning

In practice, I've had the tpms warning twice. Once was valid, one tire was getting low (slow leak), and the other time there was no good reason. In the latter case I bumped them all about 5 lbs (light went out), then dropped them the same amount a few days later (light stayed off).

 

Well surprise, SURPRISE !!!