My z4 has been pulling to the left for a while but since i dont drive it much and im always busy i have not got round to sorting it. Today i took it for four wheel laser tracking which confirmed it was my tracking out. On the way home it still felt the same. I decided to check my tyres for air and my front left only had 9psi in. I assume the tyre sensor has a fualt or is there any way they have been turned off by the prvious owner? 2006 3.0 SI BTW. ANY LIGHT ON MY TOPIC WOULD BE APPRECIATED. cheers
TYRE PRESSURE SENSOR
- Thread starter kevdix
- Start date
If they have activated at any time they have to be reset and perhaps that had not been done.
Just out of interest I had a slow puncture on mine and the sensor would detect it and activate every couple of weeks and I would just inflate the tyre and reset the sensors and wait until it happenned again until I got around to changing it.
Just out of interest I had a slow puncture on mine and the sensor would detect it and activate every couple of weeks and I would just inflate the tyre and reset the sensors and wait until it happenned again until I got around to changing it.
Half Colin
Senior member
Just to clarify, the European Z does not have tyre pressure sensors. It uses the ABS system to measure the difference in rotation between wheels on the same 'axle' i.e. front or rear. When the pressure drops in one tyre the rolling radius changes and so the wheels rotate at different rates. The system uses this to indicate a loss of pressure in one tyre. It's all in the driver's manual. 
Half Colin said:Just to clarify, the European Z does not have tyre pressure sensors. It uses the ABS system to measure the difference in rotation between wheels on the same 'axle' i.e. front or rear. When the pressure drops in one tyre the rolling radius changes and so the wheels rotate at different rates. The system uses this to indicate a loss of pressure in one tyre. It's all in the driver's manual.
He's right
Doesn't matter what the leak-rate, the sensors should see it eventually as the difference side-to-side gets more extreme. However, two punctures on the same axle may confuse the system 
Think yours may have missed a RESET sometime.
2alpsade said:Half Colin said:Just to clarify, the European Z does not have tyre pressure sensors. It uses the ABS system to measure the difference in rotation between wheels on the same 'axle' i.e. front or rear. When the pressure drops in one tyre the rolling radius changes and so the wheels rotate at different rates. The system uses this to indicate a loss of pressure in one tyre. It's all in the driver's manual.
He's right
Think yours may have missed a RESET sometime.
Indeed it is not a pressure monitoring system, it purely measures the difference in rotational speed of the four wheels (USA has actual pressure sensors in the wheel), it needs approximately 1 Bar of differential pressure in a wheel to cause the Tyre Puncture Warning System (TPWS) to activate.
This information was gathered using experimental methods.......I had a slow puncture for a few months (1 Bar in 2 weeks)
sars said:Indeed it is not a pressure monitoring system, it purely measures the difference in rotational speed of the four wheels (USA has actual pressure sensors in the wheel), it needs approximately 1 Bar of differential pressure in a wheel to cause the Tyre Puncture Warning System (TPWS) to activate.
This information was gathered using experimental methods.......I had a slow puncture for a few months (1 Bar in 2 weeks)
Yep - had similar on ours. Repaired a non-leaking puncture (screw) and the tyre leaked afterwards. The bead hadn't sealed :? . However, took a week before I could get it seen-too as the car was in use every day. We were losing 5-6psi per day, and no TPWS alarm as I topped-up every day or two until it could be sorted. They're not very sensitive at all - certainly not as sensitive as I'd like
It is as sensitive as it needs to be, it is a Tyre Puncture Warning System (TPWS) to give it the correct BMW name for it, if you get a puncture it will let you know when it becomes an issue. That is to say that running a tyre with a low pressure, at speed, causes excessive temperature in the sidewall, which induces mechanical failure of the tyre I.e. a blowout.
The system will have been calibrated for a drop in pressure that was beyond what the tyre manufacturers believed to be the lowest safe operating pressure.
The system will have been calibrated for a drop in pressure that was beyond what the tyre manufacturers believed to be the lowest safe operating pressure.
Okay on the American system, the individual sensors fitted in the wheel are a pressure switch, that is once the pressure drops below a predetermined level, a circuit is completed and radio signal is sent from the device to the alarm. In practice it isn't much better than the European system, except you should replace them when fitting new tyres, so they have extra cost :thumbsdown:
If you wanted a system that continually monitored the pressure in each wheel, this would be technically difficult and prohibitively expensive to boot, how would you power the pressure sensor in the wheel.....battery..... er no....not going to last very long is it. And to what end, just so that you don't have to check your tyre pressures once a month?
So the current system is probably the best practicable system there is, better than the American system for sure. It warns the driver of a puncture, that's what it says on the tin and that what it does, it prevents blowouts and if you have ever seen or been in a car that's had one at 70+ you wouldn't bemoan it.
If you wanted a system that continually monitored the pressure in each wheel, this would be technically difficult and prohibitively expensive to boot, how would you power the pressure sensor in the wheel.....battery..... er no....not going to last very long is it. And to what end, just so that you don't have to check your tyre pressures once a month?
So the current system is probably the best practicable system there is, better than the American system for sure. It warns the driver of a puncture, that's what it says on the tin and that what it does, it prevents blowouts and if you have ever seen or been in a car that's had one at 70+ you wouldn't bemoan it.
srhutch said:
I wouldn't go that far, but I'd say it has too many limitations. It is better than nothing, and great for those that don't check pressures often (the majority of road users). We had the odd false alarm on our Mini, but generally I've been running cars with this system for many years now without trouble. The problem with the wheel-located sensors is the batteries eventually die, so you end-up faffing with them to re-fit either with new tyres or when the system goes tits-up- and they used to cost a lot to source. Don't know the costs, now, though.
The biggest issue I have with the comment that it's a TPWS is that owners will be running with a combination of run-flats and non-RF (not the same car, obviously) and as a non-RF-fitted car owner (Alpina's do not have them fitted, ever, but we have the same TPWS system as fitted to RF-equipped cars), I'm not too happy to be losing this much pressure prior to getting a 'bong' to warn me. By then, it may be too late and a low pressure may have caused an accident. On RF-equipped cars, it's not quite so much of a concern. So, IMO, it's a bit too much 'one-size-fits-all'.
Half Colin
Senior member
I think some people are expecting too much of the system. It doesn't alleviate the need to regularly check tyre pressures. I keep a small digital pressure gauge in the car and check my pressures once a week and before each long journey. It only takes about 2 minutes. If you want a true pressure monitoring system they are cheap enough Maplins has one for £100.
http://www.maplin.co.uk/wireless-tyre-pressure-monitoring-system-390208?c=froogle&u=390208&t=module
http://www.maplin.co.uk/wireless-tyre-pressure-monitoring-system-390208?c=froogle&u=390208&t=module
I certainly expect very little from TPWS, as should other owners. It's a back-up to your normal running checks, no more.
Both of our cars are checked weekly (more often if tyres have been recently changed) and both have pencil-type gauges in the glovebox in case of a 'bong'. Saves wasting the local tyre fitters' time (and usually Mrs2Alps travels outside their usual opening hours so I would be required to perform the rescue :roll: ) and 1st thing she would do following an alarm on the Roadster is look at the tyres for obvious flats, and check the pressures if necessary before calling the 'emergency service'. A 1 bar deflation on our cars is obvious from the tyre shape (as I well know ). That horrible tyre repair gloop will not be used unless it's an absolute emergency :thumbsdown:
Both of our cars are checked weekly (more often if tyres have been recently changed) and both have pencil-type gauges in the glovebox in case of a 'bong'. Saves wasting the local tyre fitters' time (and usually Mrs2Alps travels outside their usual opening hours so I would be required to perform the rescue :roll: ) and 1st thing she would do following an alarm on the Roadster is look at the tyres for obvious flats, and check the pressures if necessary before calling the 'emergency service'. A 1 bar deflation on our cars is obvious from the tyre shape (as I well know
). That horrible tyre repair gloop will not be used unless it's an absolute emergency :thumbsdown:mine comes on every few months, usualy put 32 psi in then reset it. comes back on when preasure gets below 27psi. i have a slow leak from the bead but not bad enough to sort as ill need a new tyre soon.