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Tyre Pressure Sensor false positive

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Hi Guys,

got an alert while driving from Sydney to Canberra that my tyre pressure was low - see picture. The outside temperature was dropping had been 18 in Sydney and is show as 10 in picture and this may have caused it? I had it happen back in Feb when it started getting colder and just filled it up (was at 40psi so put it back to 42). Both times filling the tyre to 42, reseting the sensors didn't remove the message. I reset by pressing both scroll wheels and this made it go away. anyone else had this happen?
 

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Hi Guys,

got an alert while driving from Sydney to Canberra that my tyre pressure was low - see picture. The outside temperature was dropping had been 18 in Sydney and is show as 10 in picture and this may have caused it? I had it happen back in Feb when it started getting colder and just filled it up (was at 40psi so put it back to 42). Both times filling the tyre to 42, reseting the sensors didn't remove the message. I reset by pressing both scroll wheels and this made it go away. anyone else had this happen?
There is an option somewhere in the menus to reset the TPMS.
 
Hi Guys,

got an alert while driving from Sydney to Canberra that my tyre pressure was low - see picture. The outside temperature was dropping had been 18 in Sydney and is show as 10 in picture and this may have caused it? I had it happen back in Feb when it started getting colder and just filled it up (was at 40psi so put it back to 42). Both times filling the tyre to 42, reseting the sensors didn't remove the message. I reset by pressing both scroll wheels and this made it go away. anyone else had this happen?
Its likely your tyres were set at a much higher pressure, and that one tyre is the first to fall below the threshold for the alert. Even though they all show as equal, decimal places arent shown, so it could be 41.6 whilst the others are 42.4.
I’ve had this happen once before, so I filled the tyres accurately, then reset the tpms.
 
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thanks @paulp I will check fill and check for accuracy.

So 46 is the recommended when warm? (I have the 21s)
The cold pressure is printed on a label on the pillar as you open the drivers door.
Each version of model S is slightly different, so best follow the label for your tyre size.
Uneven tyre wear from poor inflation habits is also very quick due to the total mass. I’ve reduced my tyre wear considerably by getting a cheap compressor and a decent accurate guage.
 
I bought one of these tyre pressure gauges.
Tyre Pressure Gauge with Deflation Monitoring | Jaycar Electronics
You just pump your tyres to slightly more than the recommended pressure, then next morning when the tyres are cool I use the deflation feature to reduce it to the target pressure.
Well worth the $30 and is the top Choice recommended item.
 
thanks @paulp I will check fill and check for accuracy.

So 46 is the recommended when warm? (I have the 21s)

19s recommended 45psi, 21s 42psi, both at room temp, if you drive off on a cold morning the TPMS may show 2-3 psi lower for 10 minutes or so, on a warm day of long driving pressures will increase 4-7psi, not an issue as long as pressures are near equal on both sides of car.
 
Temperature plays an important role. The same air in tyres can drop dramatically at colder temperatures.
Tesla Bjorn has a very interesting video where he camps overnight at -36C. In the morning the tyres have preserved a frozen flat spot in the rubber when takes half and hour to smooth out, and the pressure drops at least 0.6 bar (9 psi).