Tyre pressure alarm light

[smiffyuk]

I picked up my new Yaris in July I don't do many miles so I spent the first month getting used to the 6 speed gearbox ( its the first time I've had 6 gears but the sixth gear is where all my other cars since 1980 have had their reverse gear ) and I really have to think about changing down from sixth 

About 6 weeks ago I had a strange light appear on the display and after reading the owners book concluded that it was the low tyre pressure alarm  after checking all the tyres I had one which was 2psi down this was less than the predicted 20% but I pumped it up by 3.5 psi  and the light went out  but I researched the problem and found that the reset button was under the drivers dash 

This week the light came on again and when I checked the tyre pressures they were the same as the previous check so I jacked the car up and looked for any nails or screws embedded in the tyres  and found nothing I checked all the valves for leaks again nothing so I thought I would use the prescribed method to reset the alarm and located the button just above the accelerator pedal, switched the ignition ON and pushed the button and counted the flashes but it only flashed twice ans despite keeping my finger on the button for over 30 seconds  it never flashed again  but it went out then I started the car and let it idle for 10 mins and switched it off started the car about " hours later to go up the shops and the light came on again and I went up the shops and back and the light went off 

Have I got a problem with electronic controls as the light only flashed twice or can I leave it until my next service  which is due next July

[flash22]

I had the same issue this week/last week, I put it down to the cold snap, sometimes the sensors can read low, also your pump/compress may also be reading incorrectly, that's why i use an analogue gauge

The difference between the tpms, my compressor and the gauge can be 2-3psi different, you can also drop 0.5-1psi when removing the compressor/pump (screw on type)

tpms can take up to 2 miles to adjust to any changes once you have reset it, so nothing to worry about

This is the Gauge I have, Highly recommended by lots of review sites and the press

https://www.amazon.co.uk/RACE-RX0014-Tyre-Pressure-Gauge/dp/B000VZ8S26

[smiffyuk]

The information about tps indicate that they don't alarm unless the pressure drops by 15 - 20 % mine were less than 10%  but I resolved the problem I explained before All the information about the reset button says that hold the button depressed until 3 flashes of the warning light occurs My only flashes twice but it reset the alarm light ( or reset so far ) 

[flash22]

There may have been a change in the tpms programming from factory if it hasn't come back on don't worry about it