Tyre pressure warning.

[martin j.]

Recently had a low pressure pop up a couple of times, same wheel but no pressure loss, is this maybe a sign of the abs sensor failing as this is the root of the system?

 

[adam davies]

Recently had a low pressure pop up a couple of times, same wheel but no pressure loss, is this maybe a sign of the abs sensor failing as this is the root of the system?

It could be, but it could also be one brake caliper is ocassionally binding and making one wheel turn slightly slower for a brief period which would trigger pressure loss warning. Because tyre pressure system on our cars use individual wheel speed.

 

[RUM4MO]

It could be, but it could also be one brake caliper is binding and making the wheel turn slower which would trigger pressure loss warning.

Hummmmmmmmmmm, if one wheel is being able to turn more slowly than it should be, it would be dragging along, I'd bin that idea I'd think.

Edit:- though serious overheating due to a dragging wheel brake could lead to the tyre pressure getting increased - but hopefully that would have been spotted, typically these warnings are given a label like "too high" or "low" do they not, I've forgotten.

 

[Rockbox]

Mind's done it a few times in the last six months wouldn't be the front left by any chance.
No problems with pressure loss and all is well underneath.

 

[Walone]

Mine did it recently but all pressures were OK, I don't recall it saying which wheel either and the error code didn't mention which wheel.

 

[martin j.]

If I switch the engine off and then ignition back message says right front, will check disc/wheel temp if it happens again.

 

[dereks01]

Big swings in weather temperatures can slightly change the tire pressure so this often happens on hot days especially on long journeys. The way VW detects pressure loss is not the best

 

[SuperV8]

Hummmmmmmmmmm, if one wheel is being able to turn more slowly than it should be, it would be dragging along, I'd bin that idea I'd think.

Edit:- though serious overheating due to a dragging wheel brake could lead to the tyre pressure getting increased - but hopefully that would have been spotted, typically these warnings are given a label like "too high" or "low" do they not, I've forgotten.

These cars don't directly measure tyre pressure - which would be effected by temperature.
They 'measure' (actually calculate) it indirectly via wheels speed sensors - looking for small deviations on wheel speed over extended driving.
If you imaging how hard that must be - determining small variations in wheel speeds which driving arround twisting roads compared to a 'calibrated' number.

When you confirm tyre pressures are all equal - it goes through a calibration process for a certain distance, so while you drive it tries to determine the expected rotations per mile. Obviously when you steer all you tyres are now going different speeds!

To give it the calibration the best chance of success in my opinion you should try do a TPMS calibration on a straight road.

 

[RUM4MO]

I was, with tongue in cheek, suggesting indirectly, that an increase in tyre pressure due to the tyre/wheel over heating, would lead to an increase in the effective rolling radius, and so the system might/could be translating this into a pressure change - as, as you said, that is what/how the system works out any changes in "pressure".

 

[LeylandVCDS]

I used to get random nearside rear warnings, when the pressure was absolutely fine. It was only when i had the tyres changed that it was found the alloy had a slight buckle in the rim (obvious when the wheel was on the balance machine). Picked up a replacement alloy rim from ebay for £60, had the new tyre transferred to that new rim, and haven't had one single false trigger since. It's worth checking to see if your rim is running true.

EDIT, had a false warning the other day in the extreme heat, no specific wheel mentioned in the errors. Switched off and reset system, and all fine since. Just putting that down to expansion and pressure increase because of direct sun