TPMS Does it work?

[jazz]

Just wondered if anybody has faith in the TPMS System?
My wheels have recently been refurbished and I am not sure the tyre pressures were checked.
Found the front wheels to be 10-15 PSI low.
I reset the pressures to what they should be and set the pressures in the menu system.
I have once again managed to "Iherit" one tyre that looses pressure, I have not found a nail yet!
Maybe a buckle or a leaky beading.
So do I need a flat tyre before a fault is posted?

[noscream]

I have found my Tyre pressure warning system works well.

I had a leak in my valve which I took to the garage, claiming a slow leak 3-5 days (suppose it depended on how good a seal the dust cap made).
They took it off said they could find no damage but the valve was faulty..... FOC.

Tyre was 33 psi, warning came in at around 24 psi.

If you are losing air and can find no damage, as a precaution, replace your Tyre valve. (I've had 3 part fail in 5 years).

The TPMS just uses the pulse sensor and an algorithm. and works out the difference, so it can be different depending on your tyre fitted.
The calculation is approx 25% of normal tyre PSI (which you set when you press the pressure ok button in menu).

Valve, cheap, 15 min job. See YT.

[jazz]

Noscream,
Thanks for the reply.
I agree that would be a cheap elimination route.
I must say that the pressures for the tyres surprised me 42PSI fronts and 39PSI for the rears. Michelin Sport 4 245/40 ZR18 XL fitted.
Feeling the bumps a little more now pressures are where they should be.

[porty]

I'm sure that my TPMS doesn't know the actual pressure of the tyre as it just has normal dust caps on the valves. I think my TPMS uses the ABS / traction control monitoring sensors to see whether a wheel is going round more times than the others (a partially-deflated tyre will have a smaller circumference than a fully inflated one).

[Crasher]

There are two different systems, wheel speed from the ABS or direct monitoring with in tyre sensors.

[jazz]

Experience now tells me it does work.Just getting on the motorway and the tpms error showed up. No steering problem at the time so as I was on my way to A&E risked it. Once i could release myself from the A&E queue, luckily the casualty had another person to stay with them. Front offside tyre flat at the bottom.{Leave it!) Tyre was not repairable and getting on the limit as was the other front tyre was also, so two new tyres later...As it happened an MOT was looming so just got new tyres a little sooner.