Tyre pressure sensors issue

My trophy connect zs has recently been telling me my tyres are on 1.9 I check at the garage and tyre pressure is fine - anyone rise had this issue ? Any fix for it rather than having to go to garage it’s about 35 min drive away so not convenient to a dealer ?

What pressures are you reading using your own gauge?

if your tyres were cold, the pressure may have dropped to 1.9, driving will heat them up and the pressure will rise again. Mine dropped from 2.3 to 1.9 when it was 0 degrees.

Alb said:

What pressures are you reading using your own gauge?

Click to expand...

2.8

Bluesparky said:

if your tyres were cold, the pressure may have dropped to 1.9, driving will heat them up and the pressure will rise again. Mine dropped from 2.3 to 1.9 when it was 0 degrees.

Click to expand...

They are 2.8 so big difference

I have set and double checked my tyre pressures with two different type’s of pressure gauges.
I set the pressures all at 2.7 Bar ( approx 42 psi ).
I have just checked the pressures via the App and they are all equal at 2.6 Bar.
That is close enough where I come from .

2.7 Bar is 39 PSI m8

Bricktop X PWR said:

2.7 Bar is 39 PSI m8

Click to expand...

Thanks for comment.
It was only intended as an approx measurement ( see above ) and perfectly accurate readings would have been better.
It was intended as a ball park figure, so that the OP could set all pressure equally, then hopefully prevent receiving the constant TPMS warnings all of the time.
The imbalance caused by incorrectly set tyre pressures, and different rotation speeds of each tyre, was likely cause of triggering the constant TPMS warnings.
Yeah - If we want to be 100% totally accurate then 2.7 bar converts to 39.160189187 PSI.
But I really doubt the car or standard DIY tyre pressure gauge has the ability to be that accurate TBH.
I have set my tyre pressures to the recommended 2.7 bar bang on.
Then checked and double checked them with three different types of tyre pressures gauges.
Each gauge returns a very close accurate reading across them all.
Then using the App to verify these readings is a bit hit and miss.
A lot of different factors, like the weather etc tend to return different results on different days.
So even if the pressures were ALL equally incorrect by the 3 PSI margin in question, then honestly I doubt the system is even clever enough to pick this up myself.
Large differentials across each tyre is an easy target for the TPMS to focus in on.
MG appear to have opted for TPMS system were sensors are fitted inside the rim of each wheel.
These sensors rely on power supplied by a flat coin cell battery.
On VAG vehicles, the TPMS system works by using the ABS braking system, that is able to monitor and cross check the turning speed of each wheel many times in a few seconds.
A under inflated tyre with a possible issue, turns at a different speed than the non affected tyres.
The TPMS system detects the problem and then triggers a possible TPMS fault to the driver on the dash panel.
It’s a more polished system, that prevents relying on cell batteries in each wheel I think.

Lovemyev said:

These sensors rely on power supplied by a flat coin cell battery.

Click to expand...

Is this confirmed or an assumption?

The TPMS doesn't give readings until a certain wheel speed is reached for a certain time. I assumed that this means that it somehow scavenges a little kinetic energy from the wheels' rotation (e.g. a magnet loose in a coil).

Lovemyev said:

Thanks for comment.
It was only intended as an approx measurement ( see above ) and perfectly accurate readings would have been better.
It was intended as a ball park figure, so that the OP could set all pressure equally, then hopefully prevent receiving the constant TPMS warnings all of the time.
The imbalance caused by incorrectly set tyre pressures, and different rotation speeds of each tyre, was likely cause of triggering the constant TPMS warnings.
Yeah - If we want to be 100% totally accurate then 2.7 bar converts to 39.160189187 PSI.
But I really doubt the car or standard DIY tyre pressure gauge has the ability to be that accurate TBH.
I have set my tyre pressures to the recommended 2.7 bar bang on.
Then checked and double checked them with three different types of tyre pressures gauges.
Each gauge returns a very close accurate reading across them all.
Then using the App to verify these readings is a bit hit and miss.
A lot of different factors, like the weather etc tend to return different results on different days.
So even if the pressures were ALL equally incorrect by the 3 PSI margin in question, then honestly I doubt the system is even clever enough to pick this up myself.
Large differentials across each tyre is an easy target for the TPMS to focus in on.
MG appear to have opted for TPMS system were sensors are fitted inside the rim of each wheel.
These sensors rely on power supplied by a flat coin cell battery.
On VAG vehicles, the TPMS system works by using the ABS braking system, that is able to monitor and cross check the turning speed of each wheel many times in a few seconds.
A under inflated tyre with a possible issue, turns at a different speed than the non affected tyres.
The TPMS system detects the problem and then triggers a possible TPMS fault to the driver on the dash panel.
It’s a more polished system, that prevents relying on cell batteries in each wheel I think.

Click to expand...

And................
No.
You've said it all really!

Great explanation which will educate folk!

I know you said 'approx' but I had a 'Bowfer' moment and had to correct you .

He got banned dont you know

I might have said, because this is how I do it, mentioned the actual pressures, then mentioned how I always add 1 PSI more than required, to account for the small loss when you take off the airline.

I only changed my tyres the other day and should have looked at the TPMS whilst the wheels were off, but I was sidetracked..........to the cafe round the corner and a coffee and toasted teacake combo.

Coulomb said:

Is this confirmed or an assumption?

The TPMS doesn't give readings until a certain wheel speed is reached for a certain time. I assumed that this means that it somehow scavenges a little kinetic energy from the wheels' rotation (e.g. a magnet loose in a coil).

Click to expand...

Well ...... I have a theory that the early MG EV models MAYBE using the sensors that may contain the coin cell batteries to power them and latter models MAYBE the same ?.
So yes I am making an assumption really.
The original ZS EV and I think the early MG5 had a similar more basic TPMS set up.
Each sensor were individually programmed to that precise location on the car at the factory.
If you then carried out a wheel & tyre rotation, it does not have the ability to relearn the new location on the car.
It will read the tyre pressure correctly, but in the wrong location on the car after doing the rotation.
Ideally the new locations would need programming into the car after the rotation.
This is taken from the MG manual.
"TPMS uses pressure sensors built into tyre valves to continuously monitor pressure and transmits signal to ECU inside the vehicle using RF signals".
Powered used from the coin cell battery .
One MG5 forum member had a the valve inflation adaptor damaged on his car.
His local tyre shop was able procure a new third party valve adaptor and it was refitted to the original OEM tyre sensor, no recoding was necessary.
Because the wheel ( containing the original sensor and new vale adaptor ) was returned to the same original position on the car.
IF the sensor is powered by a coin cell, it will likely be sealed inside of the sensor with resin.
The first photo below, is of the OEM sensor and valve adaptor.
The second photo is the OEM sensor now assembled to the new third party valve stem adaptor.






The later MG EV's does appear to have a TPMS system with a relearn facility incorporated into the system.
Making tyre rotations easier as reprogramming the new locations is not necessary.
Are the sensors fitted with batteries on these later models ?.
I don't know, but I can't understand how the sensor is receiving power, to transmit a RF signal to the car otherwise ?.
The TPMS system on many of the VAG vehicles, uses a speed sensor via the ABS system.
This is powered by the 12 volt system on the car.

I've had my car nearly 2 days and it's picked up a pressure issue with 1 wheel in the first 24 hours, then another 2 in the following day.

I've been over all tyres with my pump and one was about 2.35bar from the original 2.4, but ironically it was the one that the car said was still ok.


Still shows them as low though. And as I understand it, you can't tell the car that you know better and force a recalibration like you can on other cars?

markw said:

I've had my car nearly 2 days and it's picked up a pressure issue with 1 wheel in the first 24 hours, then another 2 in the following day.

I've been over all tyres with my pump and one was about 2.35bar from the original 2.4, but ironically it was the one that the car said was still ok.

View attachment 23989
Still shows them as low though. And as I understand it, you can't tell the car that you know better and force a recalibration like you can on other cars?

Click to expand...

Mark - Try re-inflating ALL four tyres to 2.7 Bar ( 40 Psi ) and then let the car relearn and reset the TPMS warning on your next short trip.
Had similar on our Trophy LR a few months back.
First it triggered the N/S/F then it triggered the O/SF then the N/S/R and then O/S/R warnings !.
No punctures found, just corrected all pressures to 2.7 Bar and all has been fine after.
There is no manual reset tyre pressure button, its a self learning facility.
On my wife's Fiat 500 you have to manually reset the TPMS after you have inflated the tyres.

Isn't the Mk2 set at 2.8 bar?

Rifleman said:

Isn't the Mk2 set at 2.8 bar?

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2.8 Bar is 100% correct according to the indent plate on the car of course.


The difference between 2.7 and 2.8 is negligible considering one of the OP’s tyres was only reading 2.35 Bar.
It is very likely that this is the cause of the TPMS trigger.
I really doubt that the system is that sensitive that is capable of detecting that small difference 2.7 & 2.8 Bar TBH.
There has to a built in margin for ambient temperature changes etc etc.
2.7 Bar = 39.160 Psi.
2.8 Bar = 40.610 Psi.

Rifleman said:

Isn't the Mk2 set at 2.8 bar?

Click to expand...

Interesting, I was just assuming it'd be delivered correctly configured. I'll have to put some more air in it!

I am willing to bet, if the affected tyre has not developed a slow puncture, then resetting all of the tyres to the recommended pressures, will cure the TPMS warning.

My car did the low pressure thing left rear low pressure, all I did was re check all tyres adjusted so same as tyre placard in right side door b pillar, and 3,000 km later no problem and did not have to re set anything,just clear message from phone app.