# TPMS - Tyre pressure lost alert



## tfsifreak (Nov 5, 2015)

Hi all

This morning while travelling on the M4 i received a Warning - Loss of pressure in the tyres message. I slowed down and went to the left hand lane and it seemed to me car stability was affected but it might have been entirely psychological. I have made it to my destination driving slowly and after parking for 2 hours, no tyre appears to have deflated. I'll check the cold pressure in them asap and store the pressures in the system.

I am wondering if this is a genuine alert or a false positive - as I have resetted the whole VC / MMI and did not store again the tyre pressure after the reset and the tyres do not appear to be affected.


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## Arbalest (Feb 27, 2015)

You're not the first to report this problem. See thread 'Issues with tyre pressure warning?' that commenced last Nov.
Does seem to be a random occasional glitch; obviously a bit alarming if you get such a warning as you're driving along especially on a motorway. Hope it turns out to be a one-off for you.


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## noname (Aug 20, 2015)

one tyre ore all 4?
because after a 500 km trip, I did receive the alarm to check all tyres but is normal because the system warns you wether the pressure is less or more than the set and a long travel heat up tyres and so the pressures go higher


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## Hoggy (May 8, 2002)

Hi, Does the MK3 have pressure sensors in the wheels or is it calculated via ABS discs rotation ?
Hoggy.


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## tommyknocker (Feb 10, 2012)

ABS discs rotation i've been told.


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## noname (Aug 20, 2015)

Esp, it calculates how many rotations per wheel


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## Hoggy (May 8, 2002)

Hi, If using ABS sensors it would only detect a prob if one wheel/tyre was rotating faster than another. 
If all 4 wheel/tyres pressures had lowered/risen by the same amount, unlikely I know, then it would not alarm.
Had new tyres on the Burg recently, a few miles later, TPMS alarm, Oh no not a puncture on new tyres I thought.
No they had put one tyre at 41 instead of 34, :roll: so of course that wheel was rotating slower than the other 3. 
Hoggy.


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## noname (Aug 20, 2015)

Yeah faster is due a lower pressure, less circumferences and diameter.
Pro and cons of tmps with abs, it doesn't require the sensor on the valve but give the alarm over 0,5 bar out of the set.
Pro and cons of tmps with valve, give the alarm for a less variation of pressure (less than 0,5) but requires the sensor on the valve and it's not cheaper, need another unit on the car and if you change wheels you have to buy other sensors


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## Ikon66 (Sep 12, 2003)

My mk2 had this from day one, happened quite a bit in the first year but less n less now :?


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## Hoggy (May 8, 2002)

Hi, ABS system doesn't tell you which tyre, but no expensive sensors to purchase if they do play up.
My burg ABS detects the difference in one wheel speed with a pressure drop of only 4 psi, so very useful.
Hoggy.


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## noname (Aug 20, 2015)

Why not?! Use the same calculating system for the traction/esp.. The sensor is the same but it doesn't mean it works only when you brake..


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## brittan (May 18, 2007)

Happily the system on the TT is properly conceived and will identify the problem tyre.


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## Hoggy (May 8, 2002)

brittan said:


> Happily the system on the TT is properly conceived and will identify the problem tyre.


Hi, Better still then. No expensive sensors & locates which tyre. Excellent.
Hoggy.


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## noname (Aug 20, 2015)

http://www.audi-technology-portal.de/en ... ing-system


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## Hoggy (May 8, 2002)

ManuTT said:


> http://www.audi-technology-portal.de/en/chassis/brakes-wheels/tire-pressure-monitoring-system


 Hi, Clever. 8) 
Hoggy.


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## tfsifreak (Nov 5, 2015)

Clever - but not sure it works as advertised there, this is what I think hapenned to me

So after my TPMS warning, the car was left alone for more than a day and then the pressure was checked with a digital portable gauge. No loss at all in any tyres. At all times I have measured the tyre pressure when cold.

The warning I received 35 minutes into my trip to work on the M4 is still unexplained - apart for one thing. 2 days before I effectively adjusted the tyre pressure and did not store the new pressure. Then had only short trips in the car at around 40 mph or so. So maybe that TPMS warning 2 days later while driving relates to this. That is the only way I can explain it if I did not suffer a flat tyre of some kind, and if so, I would have at least expected to see lower pressure after 24+ hours in one of the tyres. BTW the warning I received did not identify which tyre was at fault (does that mean all 4?).

I have just now topped the pressure in all tyres then immediately stored the new pressure in the MMI. I just hope I do not get anymore motorway warnings as they are distressing.


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## noname (Aug 20, 2015)

The alarm will shows as soon as the car checks the pressures but it'll remain until you set the new value..with cold tyres.
I don't know exactly your error but the image of the car in the vc will shows in red which tyre you have to check..if you saw all tyres red it could depends from too low or too high pressure..temperature too cold outside or like in my case,after 500km so tyres too hot


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## Hoggy (May 8, 2002)

Hi, If all tyre pressures have risen or dropped by the same amount, (unlikely I know) would it still alarm ?
Hoggy.


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## noname (Aug 20, 2015)

yes! all pressures can change at the same time only for an external factor that can modify all like a low temperature or a long trip


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## brittan (May 18, 2007)

If all tyre pressures rise or drop by the same amount I would not expect an alarm.
As far as I know the system will only identify a specifc tyre when there is just the one tyre with a suspect pressure.

Maybe adjusting the pressures, not resetting the system and then doing short trips has something to do with it? Short trips would probably involve a lot more corners than a long trip where A-roads or motorways are used. Lots of corners by themselves would cause more speed differences both between tyres on the same axle and between front and rear tyres.
Because of that, the system may need the car to drive in a straight line for a certain distance in order to make a sensible comparison of wheel speed difference. Maybe the short trips didn't allow that and the motorway trip did.

Maybe . . . 

At least it's one of the warning systems where it's relatively easy to conduct practical experiments.


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## noname (Aug 20, 2015)

Look, if you set 2 bar, if one or two or four tyres change pressures, the car will give the alarm because you set 2 bar so that's the value to respect and it has to warn you If is lower or greater.

Of course pressure don't change so easily with short trips..I said my experience almost 500 km to get the alarm..
Instead, when I had a nail, it was sufficient one rotation of the wheel to get the alarm that my one tyre was lower on pressur than the others


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## Hoggy (May 8, 2002)

Hi, TPMS using the ABS sensors doesn't know the pressures, only the rpm of wheel rotation & in the latest Audis, wheel vibs. so I'm sure one or more wheels rpm etc would have to be different to the others to cause an alarm.
Hoggy.


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## sherry13 (Oct 8, 2013)

Yeh my back left keeps popping up as a problem, just a few months after my local dealer checked it and said it was ok and reset it.

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## tfsifreak (Nov 5, 2015)

Interesting feedback from all thank you. 500 Km to alarm because the pressure is dropping ever so slowly is fine with me. Alerting immediately because there is a nail is even better 

But I find it weird that having changed the pressure manually, and without storing the new value in the system, I did not have the alert until 2 days later. I am siding with Brittan explanation here - and as it is based on wheel rotation, it is reasonnable to assume it takes some rotations to gather enough data - depending how one drives at that time too - to collect and compare the values calculated to the ones stored.


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## noname (Aug 20, 2015)

In my case, I received the alarm after 0,4/0,5 bar so I don't think you changed the pressures so much..
Maybe after two days/many km, the car starts to think that the actual pressures are not the same in memory for a long time and gives the alarm..


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## sherry13 (Oct 8, 2013)

It's potentially quite dangerous, that whole "cry wolf" scenario where the next time it goes off you think not again, and end up with a problem. It's also really annoying because Audi's warning sounds are irritating enough as it is!

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