Tyre Pressure System Playing Up

[CallumFox5]

Hi all,

So I have been having issues with my tyre pressure management system playing up, where it will just ping on the dash that either the front left or front right tyre has lost pressure, but it won't have.

At the weekend I made sure both my tyres on the front were at 33 PSI and reset the computer with the new values, get in the car Monday morning, it's saying I have lost pressure in my front right tyre, but when I check the pressure today when I got the chance, it is still at 33 PSI.

It's frustrating as either have to check tyres every time and reset the computer, put up with the dinging every time I start the car, or just reset the computer and ignore it, not that I would rely on the system to tell me if I had a problem anyway.

I do have a service next month for the car, do I bring it up with Seat or will they just charge me for replacement parts which won't sort it out?

 

[matthab]

33psi seems a little low, what is the car?

The pressure system runs off the ABS system so there maybe a fault in there. Have you got a scan tool handy?

 

[CallumFox5]

32 PSI is what it says in the fuel flap sticker for comfort.

It's a Mk3 Leon 65 plate. 1.4 litre.

I've been told that the system isn't in the tyre when I went to local tyre place when it first happened to see if the sensors were bad, they said that it is in the wheel arch but not sure how true that is

Don't have a scan tool I am afraid.

 

[matthab]

You could try upping the pressures to 35psi as I thought it was 35front 32 rear. The system is generally very accurate so its upset about something.

The system is not on the wheel arches its done off the ABS sensor in the axle. It compares the rotational speed of the wheels to see if they are out.

 

[CallumFox5]

But if you set the values surely it doesn't matter what pressures you have set? It detects the drop from the pressures you put in.

 

[RUM4MO]

But if you set the values surely it doesn't matter what pressures you have set? It detects the drop from the pressures you put in.

True, it will accept the next data it takes in from all 4 wheels and start from there as a reference. The only thing that might be an issue is if you use very low tyre pressures, and the car sits out in the sun, one side will vary from the other and maybe that is upsetting these systems, but surely VW Group or Bosch who provides them with with the ABS equipment, would have tested it for both lowish pressures for each model and the "in sunlight" or "in shadow" situation. A friend who worked with me, inside a secure building and so no windows where we worked, could tell the weather by checking the stats on his Ford Focus, ie by checking the tyre pressures remotely on his phone.

I've had one error in that system on a 2015 VW Polo 1.2TSI, and no true warning although I got a puncture, car was left in the garage for 4 days and a tyre went completely flat. On my 2011 Audi S4, I've also had one false warning and a few genuine warnings as my winter tyres seem to leak slightly at the valve apertures!

Edit:- on the question of what happen if you report this, I can't see you avoiding paying for a full diagnostics check, maybe 15 minutes tech time or up to £65, just for checking logged codes and reporting back to you, that unfortunately is why so many people find the need to buy a good "all systems" scan tool - for most dealerships we are but cash cows it seems, okay they are a business, but main dealerships do like to visit your wallet very deeply.

 

[CallumFox5]

To be honest I don't really rate the system highly, I have had a puncture on my front left from hitting the corner of a square weight in the road that somebody swerved late for, knew I blew my tyre, managed to crawl to somewhere safe, no warning from system, got the spare on, drive about 2-3 miles with spare on, then the system tells me I have lost pressure in my front left .

It is always the front tyres that it pings for. Never the rear ones.

I can set the tyres to 35 front 32 rear but I wouldn't say that solves my problem.

 

[RUM4MO]

My first and so far only experience of a false warning with the 2015 Polo 1.2TSI was both concerning and annoying - okay if it had been a true warning then I would have had other thoughts about it. We were on a motorway and visiting my MIL who was in hospital, so I left the motorway as soon as possible, started driving up side roads so that I could find a safe place to stop and check the tyres, and every time I thought I had come to a safe quiet place to stop I was getting pushed on by lorries - life can be like that some times, very annoying. Tyres looked okay, I reset the system and carried on, when back home I checked the tyre pressures and they were all correct!

 

[SRGTD]

@CallumFox5: as @matthab has said; the Leon’s TPMS uses the ABS sensors to monitor the rotational speed of the wheels (it’s an indirect TPMS system).

When the system’s working as intended, if it detects a drop in pressure in one tyre because the wheel with that tyre mounted on it rotates at a slightly different speed to the other wheels, the system will trigger a low pressure warning.

However, you’ve said that you’ve manually checked the pressure of the offside front tyre that’s triggered the warning and it’s correct (and presumably checked all the others too), you’ve reset and stored the values and the low pressure warning is still triggered, my money would be on you having a faulty ABS sensor.

 

[CallumFox5]

Yeah, had a big drive Saturday, made sure all my pressures were correct Friday evening as it had been pinging all week, stored the values and then it was pinging a day later.

Is there a way to check if I do have a faulty sensor or shall I just wait for the service next month and bring it up with Seat?

 

[SuperV8]

Hi all,

So I have been having issues with my tyre pressure management system playing up, where it will just ping on the dash that either the front left or front right tyre has lost pressure, but it won't have.

At the weekend I made sure both my tyres on the front were at 33 PSI and reset the computer with the new values, get in the car Monday morning, it's saying I have lost pressure in my front right tyre, but when I check the pressure today when I got the chance, it is still at 33 PSI.

It's frustrating as either have to check tyres every time and reset the computer, put up with the dinging every time I start the car, or just reset the computer and ignore it, not that I would rely on the system to tell me if I had a problem anyway.

I do have a service next month for the car, do I bring it up with Seat or will they just charge me for replacement parts which won't sort it out?

Did you set the pressure when the tyres are cold? - i.e. not after a journey. Tyre temperature effects the pressure.
Also I would check front & rear tyres - then reset.

 

[R.Bot]

The system must be sensitive, using wheel rpm to flag tire pressure issue. Is it just using ABS sensors, surely road speed / steering angle must be factored in too somehow, stupid question but why doesn't it trigger on long sweeping bends etc?

 

[RUM4MO]

The system must be sensitive, using wheel rpm to flag tire pressure issue. Is it just using ABS sensors, surely road speed / steering angle must be factored in too somehow, stupid question but why doesn't it trigger on long sweeping bends etc?

No, it is not very sensitive so using ABS wheel data is good enough, I'd hazard a guess that fully operational system like the type VW Group to most cars needs a change of 5psi to trigger a warning - remember that is a guess for the magnitude of pressure change in a wheel relative to the others to indicate that a change of 0.5psi would not trigger a warning.

 

[Big Col]

do you have the same tyre brand and tread depth across axles ?

are you setting the pressures when they are cold ?

i've found the TPMS system to be hit and miss. On the Golf its like a ninja, catching a slow puncture. On the Ibiza I had a flat and it did nothing. Went haywire with the space saver spare on though....

 

[R.Bot]

No, it is not very sensitive so using ABS wheel data is good enough, I'd hazard a guess that fully operational system like the type VW Group to most cars needs a change of 5psi to trigger a warning - remember that is a guess for the magnitude of pressure change in a wheel relative to the others to indicate that a change of 0.5psi would not trigger a warning.

I meant it must sensitive to the difference in rpm between wheels. I wouldn't have thought a few psi would make a huge difference but I guess it's enough and going round corners, varying tread depth etc are all accounted for, as it seems to work, most of the time...........

 

[CallumFox5]

Did you set the pressure when the tyres are cold? - i.e. not after a journey. Tyre temperature effects the pressure.
Also I would check front & rear tyres - then reset.

Yeah always do them when they are cold!

 

[CallumFox5]

do you have the same tyre brand and tread depth across axles ?

are you setting the pressures when they are cold ?

i've found the TPMS system to be hit and miss. On the Golf its like a ninja, catching a slow puncture. On the Ibiza I had a flat and it did nothing. Went haywire with the space saver spare on though....

I don’t have the same tyre brand as I had a puncture and they didn’t have the same brand of tyre to put on same day so changed brand, so the tread depth/wear is different but if that screws the system up then that’s dumb, because what if you get a puncture?

My front right is needing changing soon so I’ll get back to the same brand.

 

[martin j.]

Tyres of the same size but different brand can have a different rolling radius but if you’ve correctly set the system I’d have thought it would take that into account, when I had an abs sensor failing it brought on the tyre light, abs and Tcs lights on together. That was in a mkII mind, might not be the same in later cars?

 

[SamM2342]

I don’t have the same tyre brand as I had a puncture and they didn’t have the same brand of tyre to put on same day so changed brand, so the tread depth/wear is different but if that screws the system up then that’s dumb, because what if you get a puncture?

My front right is needing changing soon so I’ll get back to the same brand.

Different tyres with different compounds will fluxuate differently softer tyre gets hotter and will trigger imbalance I'd try rotating tyres from front to rear and see if same tyre sets it off if it does then buy a matching set of tyres your problem should be solved...

 

[SuperV8]

I don’t have the same tyre brand as I had a puncture and they didn’t have the same brand of tyre to put on same day so changed brand, so the tread depth/wear is different but if that screws the system up then that’s dumb, because what if you get a puncture?

My front right is needing changing soon so I’ll get back to the same brand.

I really can't believe they (VAG) will design a system so dumb that it can't cope with differently worn tyres or brands.

Indirect TPMS are ONLY looking for an abnormal variance (increase) in wheel speed. This variance will be tiny compared to the wheel speed variance when you go around a corner so it must have some time to 'calibrate' the system.

My 'hypothesis' is when you press the button to re-set the TPMS what is actually is doing is re-starting a calibration sequence - so as you drive it will be measuring each wheel speed signal and also monitoring steering angle - maybe/probably even ignore any wheel speeds when you have a certain steering angle?

Do you live in a built up area with lots of turns? Maybe you could try adjusting your tyre pressure as accurate as you can - then re-set the TPMS - then go for a drive picking some dual carriage ways/motorways ways/straight roads to try and minimise steering angles to give it the best chance of determining you actual baseline wheel speed variation.

My personal experience with the system has been fine - with no phantom warnings.

Unless you have an actual wheel speed sensor problem - which I would have thought would flag a warning light!