new tyres or sensor?

[leonfr170]

my tyre sensor light came on today on the way home. i have checked my tyres and they seem fine but as its dark i can't be 100%. is it possible a sensor is playing up or should i be checking the pressures and taking to a garage before i head to work in the morning? i drive 130miles a day so don't want to rick it. if i need to change a tyre im thinking i do the pair, am i being stupid but i think a fresh pair together will work best and at least i can get rim protection on my 19s?
thanks guys in advance!!!

 

[Tam]

the light shows that there is loss of pressure in a tyre.

Easiest way to prove that is to pop to a garage and check the pressures.. if they are all the same, reset the sensor (push the button) and see if it comes on again, if it does, it could well be a sensor fault.

 

[pr0ton]

the light shows that there is loss of pressure in a tyre.

Actually, it doesn't show that there is a loss of pressure, it shows that there is a difference in one or several wheel turning speed comparing to each other and comparing to the preset level.... which is usually (but not always) caused by the loss of tyre pressure. It could be increased tyre pressure because of the tyre overheating etc.

 

[leonfr170]

well i've checked tyre pressures and they seem ok but the light won't go out. gonna call the stealers and see what they think

 

[rv2583]

hold your finger on the tyre pressure buton for about 5 seconds and it will go out ,you could have a nail in your tyre and that doesnt lower the the pressure that much straight away so you wouldnt feel it when you drive and its not vissable at first,i know this coz it happend to me.

 

[jtmac]

This happened to me and I'm not he only one. Check the pressures, if you are happy then press and hold the reset button and forget about it.

This is what I posted when it happened to me.
http://www.seatcupra.net/forums/showthread.php?t=125111

 

[chrisboyle999]

unusual loads and rubbish road surfaces can also cause spurious faults.

 

[leon1p]

I still have mine lit permanently as I haven't had a chance to book it into the dealers.. It's had a new set of tyres on the front all pressures checked regularly but it wont reset so must be a sensor or some sort of fault in the system. Happened after hitting a big puddle.. i just thought the aqua planing had fooled it but it has never reset since.. If you hold the button down it blinks off then back on with no tone.

 

[pr0ton]

it should be reseted only while moving at steady speed, because the system uses ABS sensors to monitor the wheel speeds. Otherwise it might not reset properly and warning light might light again.

 

[chrisboyle999]

I still have mine lit permanently as I haven't had a chance to book it into the dealers.. It's had a new set of tyres on the front all pressures checked regularly but it wont reset so must be a sensor or some sort of fault in the system. Happened after hitting a big puddle.. i just thought the aqua planing had fooled it but it has never reset since.. If you hold the button down it blinks off then back on with no tone.

does the lamp flash?

it should be reseted only while moving at steady speed, because the system uses ABS sensors to monitor the wheel speeds. Otherwise it might not reset properly and warning light might light again.

where do you get this information from?
to reset the system it is only a requirement to have the ignition on and the tyres at the correct pressure.

 

[pr0ton]

where do you get this information from?

I didn't get mine to light off until i did this. As it uses the ABS sensors to monitor the wheels you have to be moving to get any speed signal from the sensors, otherwise it's calibrated to 0km/h. And if for example one of the sensors is broken/dirty, it might show a signal of 0km/h even if the car is moving. I'm pretty sure i read this from the manual when i got the car. I will double check it tomorrow.

 

[leon1p]

No it comes on with the ignition and stays on constantly, when you hold down the button it goes off for a milisecond then is back on. Car moving or stationary, igntion only or running it makes no odds. I fear even when I get round to putting it in the dealers I wont know exactly what the fault is.


The whole way these work still confuse me, I know it is linked to ABS sensors even though the dealer tried tell me it was sensors inside the wheels.. But it makes logical sense that the car should be moving when it is set so that it can measure the rotations while the pressures are known to be correct.. Obviously I cant test this but can you set the pressure when not moving? Surely this just means that if you set the pressures then dont drive till the next day the car could have a flat tyre overnight and not know detect it.. Does this then mean that you never set the pressure but in fact just reset the warning? But that doesnt go with the instructions which I think would have you reset the TPM after you have adjusted them or changed tyres not just to clear a warning...

Oh I should mention my ABS works fine.


If i have a faulty sensor where would it be.. I would have thought since it uses abs all the TPM gizmos are actually just software based using the reading the ECU gets from the ABS measurements.. they wouldnt have 2 sensors on each wheel doing the same measurement would they? If it does purely use ABS why do I not have an ABS fault.

Sounds like the original poster has a similar prob.. Surely you could set one tyre at 10psi and another at 30 and reset the TCM and the car would happy until that pressures changed significantly therefore indicating that the inability to reset is not a tyre problem but a gadgetry problem?

It's all assumptions on my part but I would be interested to hear how it all plays its part.

 

[chrisboyle999]

I didn't get mine to light off until i did this. As it uses the ABS sensors to monitor the wheels you have to be moving to get any speed signal from the sensors, otherwise it's calibrated to 0km/h. And if for example one of the sensors is broken/dirty, it might show a signal of 0km/h even if the car is moving. I'm pretty sure i read this from the manual when i got the car. I will double check it tomorrow.

i dont think so.
the system uses differences in wheel rotation irrelevant of speed.
if there is a broken sensor/system fault the warning lamp flashes, thats why i asked leon1p if his was flashing.

 

[pr0ton]

the system uses differences in wheel rotation irrelevant of speed.

I'm well aware of that. I'm just saying that no tyre is 100% identical and you can only reset those differences while the car is moving. Otherwise it will be reseted to 0km/h. Not sure how much difference there should be before it gives the warning.

edit: Manual says, power on and press reset button until you hear the signal voice.

 

[leon1p]

Im doing a lot of reading here and here are some things I think I can lay down as fact(ish)..

1. I think we all agree that the new leons use Indirect Tyre Pressure Monitoring using theABS sensors and not Radio senders mounted on the valves.

2. No extra sensors are used it uses the actuall abs sensors and their respective reading.

3. False alarms can happen (Some reports of bumps) but it negates this by using a long term reading so that wheelspin or aquaplaning have more chance of being undetected whereas a deflating tyre will still be rotating differently 10 meters on.

4. ABS based TPM cannot detect minimal gradual changes in pressure, and more specifically slow equal changes in all tyres (this may depend on the algorithm used by the manufacturer I suppose)

No one seems to mention that the car should be moving or not :s

 

[pr0ton]

Quote from the manual: "Warning light appears - If the pressure in some of the tyres is lower than the pressure that DRIVER has SET, warning light appears.

edit: Another quote from the manual: "ATTENTION! In certain conditions (eg. very spirited driving, in winter or on unpaved roads), the warning light might light with a delay or might not light at all.
edit: Direct translation from Finnish manual, so the grammar is not perfect

 

[chrisboyle999]

Im doing a lot of reading here and here are some things I think I can lay down as fact(ish)..

1. I think we all agree that the new leons use Indirect Tyre Pressure Monitoring using theABS sensors and not Radio senders mounted on the valves.

2. No extra sensors are used it uses the actuall abs sensors and their respective reading.

3. False alarms can happen (Some reports of bumps) but it negates this by using a long term reading so that wheelspin or aquaplaning have more chance of being undetected whereas a deflating tyre will still be rotating differently 10 meters on.

4. ABS based TPM cannot detect minimal gradual changes in pressure, and more specifically slow equal changes in all tyres (this may depend on the algorithm used by the manufacturer I suppose)

No one seems to mention that the car should be moving or not :s

1,2,3,4 all fact.

car need not be moving.

if all 4 of yor tyres rotate at 1000rpm (for example), then the system is happy. if one wheel, for any reason, begins to rotate faster (dont know how much faster) for a set period (dont know what the period is) will trigger the alarm. the system can be fooled by, uneven loads, towing, long sweeping corners, poor surfaces.

this all happens irrespective of the starting pressure, be it 10psi, or 50psi. its up to the driver to ensure correct initial pressure. and as we all know tyre pressures change (slightly) while moving.

Quote from the manual: "Warning light appears - If the pressure in some of the tyres is lower than the pressure that DRIVER has SET, warning light appears.

edit: Another quote from the manual: "ATTENTION! In certain conditions (eg. very spirited driving, in winter or on unpaved roads), the warning light might light with a delay or might not light at all.

exactly.

 

[chrisboyle999]

pr0ton, your english is better than most english (british) people.

 

[pr0ton]

Confirmed information: After reset, the system calibrates itself after vehicle speed is over 20 km/h.
So, no matter if you reset it while moving or not.

edit: The system presumes that the readout from the sensors after resetting is the 'normal condition'. So if you come home and park the car for the night and reset the pressure sensors. During night you lose 1bar from one of the tyres and in the morning you start driving. After you reach 20km/h the system calibrates itself with the current condition. One thing learned. Do not reset the pressures, if you're not going to drive the car right after it, to calibrate the system.

 

[leon1p]

It's all much clearer now guys, and pr0ton your last post really helps answer the main thing that confused me.

Im going to book car into the dealers at the start of november when I have time off and see what they say about getting it working again. Might try to think of anything else that's a problem but I think that's my only issue.


leonfr170: Have you been able to reset yours successfully yet?