How trustworthy is the TPMS ?

Evening
Had low tyre pressure warning few days ago in a cold morning. Didn't use the car since. Tried to reset the warning today but found out the TPMS readings is 3 bar less than from a pump gauge. Same result from 2 different pumps.
Anyone has experienced similar discrepancy?
Could it be faulty sensors but all 4 of them seems too much coincidence!
Any comments in addition to just take the car back to the dealer for a check up and recalibration?
Thank you
Ben

Mine seem to be pretty accurate compared to my digital pressure gauge.

I think your pump gauge is more likely inaccurate than the TPMS. I find TPMS agrees with my good quality hand held gauge.

GeorgeC wrote: I agree with Bill and Chris.

I find pumps a bit off to the extent where, out 3, one (a Presta fitting) up to 100psi is spot on,
the other two (Schrader fittings) are +8 and -2 psi respectively, at 30psi!
The new Digital gauge is spot on!

These are the pumps I used with digital gauge. Are the gauges inaccurate?
Thanks
Ben

They won't be far off but won't be properly calibrated either. I use a separate analogue dial gauge which has been calibrated, according to that the tpms on Spare Jimny is within a half psi.

Hi,

When you say 3 bar out do you mean 3 PSI? Gauges fitted to pumps are not really all that accurate, they even say use a good quality gauge to check the tyre pressure.

+/- 1 or 2 PSI is not really a problem just as long as they are all the same. I doubt that TPMS is within +/- 1 PSI either. Get a good gauge and if possible get it checked. The pumps at garage forecourts should be checked and calibrated from time to time otherwise they would run in to trouble if someone had an accident.

TPMS is most useful for spotting a leak, either slow or fast given that none of us do the weekly check anymore. Same with the oil for and water for most people, gets checked when it goes in for a service.

I doubt that TPMS is within +/- 1 PSI