Tyre Pressure Warning

[MadProfessor]

Got a one year old Audi A6. Checked my tyre pressue today when filling up as the car doesn't feel right at the moment. Tyre pressure low all round at 26-28PSI instead of 41/38 but the tyre pressure warning system had not come on.

Any ideas why not? Is it faulty?

[Fourmotion]

I think the monitoring is only done relative to the other wheels, using the ABS sensor.

So if one goes down it shows the wheel moving at a different rate due to a different circumference and flags it. If they all drop it doesn't flag anything.

Hopefully someone can give a more scientific answer!

[catso]

Mine ('14 S4) brought up a low pressure warning for one tyre only, it was only a couple of psi down. I understand that temperature can make the difference especially extremes and I would imagine it is more difficult on a lower profile tyre where the relative difference detected would be less than a larger tyre.

Suggest you inflate to correct pressures and then reset the tyre monitor to suit, as mentioned above it doesn't actually measure pressure (at least mine doesn't), rather the wheel circumference/height.

[marcosgt]

Mine came on Friday after a particularly painful journey from Hampshire to Hull.

All four were reported as down on pressure and, sure enough, were all a fair way below recommended pressures when I filled them on the Saturday morning.

Not sure why they suddenly reported it...

M