New tyres but tyre pressure monitoring light came on

[turquoise]

I had a service on Tuesday, then had a tyre check and three new tyres fitted yesterday. But this morning the yellow tyre pressure monitoring light came on just a few minutes after leaving home. What's wrong? Is it urgent to get to a garage/air pump asap to recheck all tyres? Did the technicians not do a good job?
Thanks!

[SRGTD]

I suspect the TPMS wasn’t reset after the new tyres were fitted, so it was probably a false warning.

Check the pressure of all the tyres and adjust them if necessary, then reset the TPMS to store the tyre pressure values. Hopefully, the low pressure warning won’t happen again.

[turquoise]

Thank you, will try this.

[Johntheo1]

Didn't start a new thread.

Decided to test the TPM on my 3 year old Polo, pumped tyres to 2.0 bar, then reset the TPM, reduced RR Tyre by 0.5 bar to 1.5bar and went for ~ 2 mile spin, no alarm, returned, repumped tyre to 2.0 bar, went for another spin (did not reset TPM) no alarm (and not expected this time). Reset TPM again.

Why no alarm?. When I purchased the car the tyre pressures were 2.3 bar and I didn't pump them until they fell (all uniformly) to 1.9 bar, again I didn't get any alarm in falling from 2.3bar to 1.9bar, but can't confirm if the TPM was set up when the car was delivered so maybe benefit of the doubt there.

[amer6R]

Try driving at higher speed

[Johntheo1]

Try driving at higher speed

Reset TPM at 2 bar all tyres, reduced one to 1 bar, still no alarm driving at speeds up to 35 MPH (in speed limit zone).Presume its not something daft like the car having to be on the run (moving) when tyre(s) deflates. Now suspect system faulty as it didn't alarm in falling from 2.3 to 1.9 bar originally.

[Mikeso51]

Johnthe1,

My understanding of how the system works is that it compares the rotation speeds of the wheels with the “set” values, and triggers a warning if there is a significant variation. When you reset the system, it can’t actually register the new settings until the car is moving again. So if you reset the system, then change the tyre pressures without moving the car, then the system will register the last settings when you next drive the car not the ones that you first set. Hope this makes sense. Try resetting the system to say 2 bar all round, then driving the car to register these settings before dropping the pressure in one tyre to test.

Mike

[Johntheo1]

Johnthe1,

My understanding of how the system works is that it compares the rotation speeds of the wheels with the “set” values, and triggers a warning if there is a significant variation. When you reset the system, it can’t actually register the new settings until the car is moving again. So if you reset the system, then change the tyre pressures without moving the car, then the system will register the last settings when you next drive the car not the ones that you first set. Hope this makes sense. Try resetting the system to say 2 bar all round, then driving the car to register these settings before dropping the pressure in one tyre to test.

Mike

Spot on Mike,

I did that after realizing its ABS derived, I then did a ~ 3 mile run between resetting to 2.0bar and deflating to 1.5bar and doing another mile or so then, it certainly did a extended run in the few years it took to fall from 2.3 bar to 1.9bar but as all tyres fell very uniformly maybe it doesn't see this as a problem?.
My manual states "After a extended driving time with driving different speeds , the system will automatically learn the new values and monitor them"

John

[Johntheo1]

Johnthe1,

My understanding of how the system works is that it compares the rotation speeds of the wheels with the “set” values, and triggers a warning if there is a significant variation. When you reset the system, it can’t actually register the new settings until the car is moving again. So if you reset the system, then change the tyre pressures without moving the car, then the system will register the last settings when you next drive the car not the ones that you first set. Hope this makes sense. Try resetting the system to say 2 bar all round, then driving the car to register these settings before dropping the pressure in one tyre to test.

Mike

Spot on Mike,

I did that after realizing its ABS derived, I then did a ~ 3 mile run between resetting to 2.0bar and deflating to 1.5bar and doing another mile or so then, it certainly did a extended run in the few years it took to fall from 2.3 bar to 1.9bar but as all tyres fell very uniformly maybe it doesn't see this as a problem?.
My manual states "After a extended driving time with driving different speeds , the system will automatically learn the new values and monitor them"

I'd prefer a system where the "extended" time is only say a day or two but will then flag a alarm even if it requires a differential pressure of 1 bar, at least you will then have some realistic idea of a slow puncture or whatever.

John

[Johntheo1]

Johnthe1,

My understanding of how the system works is that it compares the rotation speeds of the wheels with the “set” values, and triggers a warning if there is a significant variation. When you reset the system, it can’t actually register the new settings until the car is moving again. So if you reset the system, then change the tyre pressures without moving the car, then the system will register the last settings when you next drive the car not the ones that you first set. Hope this makes sense. Try resetting the system to say 2 bar all round, then driving the car to register these settings before dropping the pressure in one tyre to test.

Mike

Spot on Mike,

I did that after realizing its ABS derived, I then did a ~ 3 mile run between resetting to 2.0bar and deflating to 1.5bar and doing another mile or so then, it certainly did a extended run in the few years it took to fall from 2.3 bar to 1.9bar but as all tyres fell very uniformly maybe it doesn't see this as a problem?.
My manual states "After a extended driving time with driving different speeds , the system will automatically learn the new values and monitor them"

I'd prefer a system where the "extended" time is only say a day or two but will then flag a alarm even if it requires a differential pressure of 1 bar, at least you will then have some realistic idea of a slow puncture or whatever.

John

Still can't raise a alarm, did approx 100 miles after resetting TPI with all at exactly 32 psi, reduced pressure in one (different to previous one) by 14 psi, to 18 psi, drove another 4 or five miles, so is my original thinking vaid, ie, that the pressure must actually fall while the car is in motion to flag this warning?.

[johntheo2]

Hallelujah!!, Tyre ptrssure monitor flagged a alarm this morning " Right Front Tyre Low Pressure" checked all tyres which all had been pumped to 32psi (2.21bar),

Right Front: 18psi

Right Rear: 29psi

Left Front: 26psi

Left Rear: 30ps

Tyre alarm up when R.Front was 10.33psi (0.713bar) lower than the averaged other 3, or 18psi lower than the 32psi reset, 36.5% of the averaged other 3 (now) or by 43.8% of the original reset at 32psi.

So, better than nothing since its not actually monitoring the pressures?.

[SRGTD]

IMHO the TPMS is just a back-up system and shouldn’t be relied on solely as a means of warning of a possible tyre under-inflation problem.

It’s good practice to manually check tyres regularly;

• For condition - I do a visual inspection for cuts, bulges in the sidewalls and ‘foreign objects’ such as sharp stones, nails, screws etc. that can become embedded in the tread when I wash my car (usually every couple of weeks). I also carry out the under-bonnet fluid checks as part of my car washing routine.

• Air pressure; I check the tyre pressures monthly and adjust as necessary. When I took delivery of my car, one of the first things I did was to check the tyre pressures. One of then had been left at the ‘transit’ (from the factory) inflation pressure, which was around 50psi . I can only assume the garage overlooked this one tyre for some unknown reason when they carried out the PDI (they missed other things during PDI too). If I hadn’t checked, I could’ve been driving round with an excessively overinflated tyre for around a month!

IMHO it’s worth investing in a mini portable compressor / tyre inflator - one that’s powered from the 12v socket - and keeping it in the car, along with a tyre pressure gauge, rather than relying on the air line at a filling station. Tyre pressures should always be checked when the tyres are cold, and depending on the distance involved, driving to a filling station could mean the tyres warm up during the journey to get there. Also, the filling station airlines can be inaccurate and it may have been some time since they were last tested / recalibrated.

Tyres are an important safety feature of a car. You’re relying on those four small contact patches of rubber to keep you safely on the roads, so a few minutes every couple of weeks / every month spent checking the condition and pressure of your tyres in a no-brainer IMHO.

@johntheo1; interesting that you have had all your tyres set to the same pressure. Normally the recommended pressure in the front tyres is higher than the rear tyres due to the additional weight of the engine and transmission that the front tyres are supporting.

[johntheo2]

I do check my tyre pressures regularly, every three weeks or so, but wanted to see if this alarm system worked in any fashion. I have never used a garage to top up in 59 years of driving, I upgraded from a ancient foot pump to a mini air compressor about 10 years ago which has a remarkably accurate pressure gauge but generally use (another ancient) Dunlop pencil gauge for the regular checks, that's why I still think in PSIs.
Yes, I do normally put 34psi in the front & 32psi in the rear but again for the above exercise I pumped them all to 32psi.

[TrebleTA]

It is a funny system yet for me it has worked when I got a friendly bolt in the tyre, was a slow loss in pressure, but triggered as I turned a cornor hit a bump and warning low pressure p.s.r. But there is a system to monitor the pressure better, I did think this was like a vaule sender like on the BMW but no this is more a cheepy but still a little helpfull. Still better with a visual before every drive.

[RUM4MO]

It is a funny system yet for me it has worked when I got a friendly bolt in the tyre, was a slow loss in pressure, but triggered as I turned a cornor hit a bump and warning low pressure p.s.r. But there is a system to monitor the pressure better, I did think this was like a vaule sender like on the BMW but no this is more a cheepy but still a little helpfull. Still better with a visual before every drive.

Thing is, even the "proper" systems have weaknesses, for instance they need their batteries replacing every so often - if indeed all the direct systems do have replaceable batteries in their sender units - plus the sender units can easily get wrecked by a clumsy tyre fitter.