Prius 2 ECO - Low Tire Pressure?

Was your pressure check at the end of an extended drive then? The tires will be hotter, reading higher pressure than they would if cold, anywhere between 3~5 pounds. A drop in ambient temperature will drop their pressure a bit too. I would bump them up, say at the nearest gas station after work.

 

Low pressures tend to flex and heat the sidewalls more, which can weaken them, this also heats and expands the air in the tyre, which increases the pressure, sometimes to over inflation, these events can lead to a blowout. Not a risk I'd take at 79 mph on a highway. Get them pumped up before the long haul.

 

This happen to me today. I have at the front 39 psi rear 36 psi . Don't know what happen . I put air in all tires and the tire pressure signal it gone now .I was reading the tiredrack booklet it said u can lose air on the tire even if it does not have a flat.

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When we were on road trip vacation the TPMS warning come on. Freaked, I pulled into a gas station and checked pressures; they all were fine. I raised them all about 4 pounds and the light went out. Later lowered them to normal: the light did not return. In other words, weird.

 

I wonder if atmospheric pressure affects the sensor, were you at a different altitude on your trip ?

 

No, near sea level, about the usual. West Coast of Vancouver Island, Long Beach area. Nice country btw.

 

OK Mendel, perhaps because the atmospheric pressure is higher at sea level than at the top of a mountain and would tend to squeeze the pressure inside the tyre such that the difference between the two triggered the sensor.

 

Thinking the car was initially set with the pressure in the 40's by the factory, the dealer didn't check the pressure, now they are 10 pounds or more less than when set, so the alarm went off.
If you reset the cars pressure gauge (computer) the light will go off and you can drive, when you put them back at a higher pressure, reset the computer.