TPMS Digital Display

[Jimota]

My youngest son became the second Toyota owner in the family after purchasing a brand new Yaris in June.  He does not have much knowledge of cars in general and approached me in a bit of a panic when the TPMS warning light came on.  After showing him how to check the tyre pressures and reset the system, he wondered why the light came on in the first place as the all the tyres were at the correct recommended pressures.  

Surprisingly, the following day my TPMS warning light came on as well but the pressures were fine with no visible damage on any of the tyres.  The TPMS reset without any problems. So, what causes this issue?  Was it a steep drop in overnight temperatures, or a slight escape of air after driving over rough surfaces.

I’ve had the same issue with a number of previous cars but never really looked into the causes.  

Any suggestions or observations would be appreciated.
 

 

 

 

[Bper]

Hi James,

As the car is new and weather is not freezing cold I would assume it could be a faulty TPMS sensor. If you haven't got a TPMS device that allows you to reprogram then I would take it in and get it checked.

My TPMS light has only came on once since ownership and that was when the tyre pressure had dropped. Taught me to check them on a regular basis. 

If your car doesn't have an onboard tyre pressure monitor then I would invest in a decent tyre pressure gauge.👍

 

[Bernard Foy]

Mine did same on a temps drop, however, when the tyres warmed up on a journey the light went off. About a fortnight later on a further temps drop it came on and stayed on during a longer journey. So when I got home I checked all tyres first thing next morning and used my compresser and Dunlop tyre gauge. Found that all tyres were not at recommended pressure and I brought them up to desired level. The TPMS actually reset itself and the light disappeared. That's my experience with low pressure light 

[jthspace]

It's happened to me twice in the short time I've owned my Yaris.  First time was a low pressure in one tyre, not much but enough to trigger it.  Second time was a bit strange.  I had parked with the car on full lock due to limited space (son's drive) and the light came on as I turned the ignition on.  I checked the tyres and all were spot on, so I drove away.  Once on the main road the warning light went off and I've not seen it since. I've checked the tyres a couple of times and they've not needed any air although I keep a small cordless tyre pressure pump in the boot "just in case".

I wondered if having the tyre under strain on full lock confused the sensor?

[Peterd23]

Quite a common occurence on cold mornings when the temperature is low and happened to me numerous times over the years in different cars. What I do now is reset the TPMS with pressures a little on the low side - not too much !, maybe 2 or 3 psi then inflate to the correct pressure. Inflation is usually needed for the winter months anyway and doing this tends to avoid the early morning surprise when it is cold but still gives the warning if the pressure has dropped due a puncture.

[Jimota]

I just thought it strange that both of our cars showed tyre pressure issues less than 24 hours apart.  Drove a distance of 22 miles today and no further problems identified.

[Jimota]

No problems with my son’s car either.

[MikeSh]

I'd imagine that new cars come out the factory with the tyre pressures on the high side and the tpms programmed to that. Then the dealer drops the pressures to the correct value (well, supposedly they do) but maybe doesn't reset the tpms calibration. As a result the correct pressures may be near the lower limit of the tpms and thus prone to nuisance alarms.

Solution is to get the pressures to what you want/need and recalibrate the system. That should give the appropriate amount of leeway for cold mornings (unless the system really is a bit rubbish).

[Roy124]

Funnily enough I had a warning today too.  This was the 3rd trip in the day and 18 deg. OSR showed Amber 27 and NSR Black 27.

On the gauge the OSR showed 26.5.

I checked all tyres which were all down 2 psi and brought up to 32/29  Later,  after  20 minute drive all tyres were 2 psi above the recommended pressures. 

All normal  and just shows,  trust the TPMS and then check all the tyres.  Incidentally the handling felt different. 

[Derek.w]

Tyre pressure is quoted for cold tyres.

[Serban]

I had this happen to me so I've reset it on cold, inflated 2.0bar rear and 2.2bar front as per recommendation and I had no issues since.