False TPMS Alert

[MakaveliX]

Was driving down a long A-Road this morning when my TPMS light came on, so did the safe thing and came off at the next junction and checked the tyres.
They were all 3 PSI over what they should be. ( Fronts should be 35, rear should be 33, but they were Front 38 and Rear 36 ) I then reset the TPMS light once the tyres had cooled down back to 35 front 33 rear

I monitor my tyre pressure closely every week so I never over or under inflate.

This is the second time since owning the car this has happened, it wasn't a particularly hot morning ( if anything quite cold ) and I had only been driving for 25 mins or so at 50mph.


Any advice regarding this ? As It's a horrible feeling to be going down a long A-Road or even motorway and then the TPMS light comes on.

Perhaps ensure the tyres are 35/33 go for a drive and then hit the TPMS set button after they have warmed up ?

I have indirect TPMS ( Mazda 3 ) which doesn't tell you the pressures via the infotainment but I believe it measures wheel rotations via the ABS sensor

[Automaton]

I had this once in a 3 series after hitting a pothole, had to check and mine are indirect to. No idea why it would go off so quickly from that, would have expected it needs a couple of full rotations to flag but there we go.

[georgeyboy12345]

Take it to a tyre shop and have them check. I bet you have a nail in one of them

[T6 vanman]

This is going to sound strange but did the A road have a very slight radius (curve) when the TPMS warning activated,

Some roads at a certain speed the steering angle & 'g' sensor does not identify any steering input but due to the radius the tyres are rotating at a differing speed and the indirect sensing uses the wheel speed sensors are reading that difference as a deflating tyre


Or you may have a tiny air leak

[MakaveliX]

georgeyboy12345 said:

Take it to a tyre shop and have them check. I bet you have a nail in one of them

The tpms system also gives an alert when the pressure increases, that's why it went off. It has happened before on a very hot day.

[MakaveliX]

T6 vanman said:

Or you may have a tiny air leak

No air leak. When I got home and the tyres had cooled down, all the pressures were spot on.
As said, it seems to give an alert when the pressure either increases by 3 psi or of it decrease by 3psi. In todays instance it had increased by 3psi and then I got the alert

[Pica-Pica]

MakaveliX said:

Was driving down a long A-Road this morning when my TPMS light came on, so did the safe thing and came off at the next junction and checked the tyres.
They were all 3 PSI over what they should be. ( Fronts should be 35, rear should be 33, but they were Front 38 and Rear 36 ) I then reset the TPMS light once the tyres had cooled down back to 35 front 33 rear

I monitor my tyre pressure closely every week so I never over or under inflate.

This is the second time since owning the car this has happened, it wasn't a particularly hot morning ( if anything quite cold ) and I had only been driving for 25 mins or so at 50mph.


Any advice regarding this ? As It's a horrible feeling to be going down a long A-Road or even motorway and then the TPMS light comes on.

Perhaps eyre the tyres are 35/33 go for a drive and then hit the TPMS set button after they have warmed up ?

I have indirect TPMS ( Mazda 3 ) which doesn't tell you the pressures via the infotainment but I believe it measures wheel rotations via the ABS sensor

Do what you say … “Perhaps set the tyres at 35/33 go for a drive and then hit the TPMS set button after they have warmed up ?”

[Pica-Pica]

MakaveliX said:

georgeyboy12345 said:

Take it to a tyre shop and have them check. I bet you have a nail in one of them

The tpms system also gives an alert when the pressure increases, that's why it went off. It has happened before on a very hot day.

Not quite true in your case, it gave a warning when the rotations were different to expected. That is what your indirect TPMS did (OK it was probably a pressure increase, but the system measured a change in rotations, that is a change in rolling circumferences)

[Aunty Pasty]

With this TPMS you do get false positives occasionally. I usually check when safe to do so or if I'm near home get there first and then check again the next morning before resetting the system.

[Shaw Tarse]

Same car as here https://www.pistonheads.com/gassing/topic.asp?h=0&... and https://www.pistonheads.com/gassing/topic.asp?h=0&...

[MakaveliX]

Shaw Tarse said:

Same car as here and https://www.pistonheads.com/gassing/topic.asp?h=0&...

I knew I made a thread about this before but couldn't find it, thanks

I'll take the advice and go for a short drive then set the tpms

Still begs the question as to how all of my tyres had increased by 3psi on a cold morning at 50mph.

I've driven much longer journeys before and never had that alert.

Edited by MakaveliX on Sunday 26th February 17:10

[Aunty Pasty]

MakaveliX said:

I knew I made a thread about this before but couldn't find it, thanks

I'll take the advice and go for a short drive then set the tpms

Still begs the question as to how all of my tyres had increased by 3psi on a cold morning at 50mph.

I've driven much longer journeys before and never had that alert.

Edited by MakaveliX on Sunday 26th February 17:10

The psi going up during a drive is quite normal. The axle rotation TPMS system is looking for differences between rotation speeds between wheels on the same axle.

[MakaveliX]

Aunty Pasty said:

The psi going up during a drive is quite normal. The axle rotation TPMS system is looking for differences between rotation speeds between wheels on the same axle.

Thanks for the info.
I checked them immediately and it was 38psi both at the front, and 36psi both at the rear.

Once I had left the car for a couple of hours they had returned to the standard of 35 psi front and 33 psi rear.

[Haltamer]

It's not unheard of, especially if you've changed tyres or have slightly uneven wear they can take a few calibrations in my experience.

With indirect TPMS I'd usually take a warning as a sign to "have a quick feel"; Music down, listen & see if there is any impact to steering / any drift imparted; If no then have a proper check at the next stop (Driving sensibly there)

If yes, activate "Oh dear" procedures :P

[xx99xx]

I regularly get false pings of the TPMS. I also don't get pings when I actually do have pressure issues e.g. the time a tyre rapidly deflated (via a pot hole) on a country lane and I had to drive (slowly) for a few hundred metres to get to a safe stopping point.

[shtu]

Yeah, it's something that happens once in a blue moon with indirect (abs-sensor-reading)) TPMS.

I wouldn't bother with the setting-while-hot idea - the system is only looking for differences between wheels. Just set them cold and it'll be fine.

[MakaveliX]

Cool thanks guys. Not gonna lie I did panic when it came on as of all the places it was a fast and long A-road

What I don't get is, I've driven for hours before and had no alert however I drive for 25 minutes this morning and it gives an alert. Perhaps it had something to do with the atmospheric pressure.

So basically if it happens again just pull over at the next safe space, ideally service station or the next exit off the motorway/carriageway ( not hard shoulder) and give it a good check. I do have greenflag as a safety net. I also check my tyres without fail every week

[cuprabob]

MakaveliX said:

I also check my tyres without fail every week

We know

[MakaveliX]

cuprabob said:

We know

Perhaps when the alert came on one tyre was at a different rotation and then shortly after when it warmed up they were the same, hence why the pressure on the front axle was the same and the pressure on the rear was the same when I checked a few minutes later.

[Zarco]

My off side front TPMS over reads by 0.1-0.2bar. Annoys my OCD, but not sure if it's a fault or just a querk of this type of sensor.