TPMS

[TonyC]

I’ve got friends staying who’ve recently bought a MG4 SE SR. They wanted to see my Trophy model as a comparison. Pulled it out of my garage to the comment, “Your passenger rear tyre looks flat!”
On inspection, yes it’s completely flat, which I will attend to tomorrow… More concerning is the fact that my car doesn’t know it’s flat… See photos! Anybody else had this happen?

 

[Tight Git]

If it has gone flat since you last stopped it won't register until you have travelled about 0.5 miles.

 

[Lovemyev]

I was just about to say the same thing, I think the wheel needs to be rotating to pick up the puncture.
Don't drive it now though, it will ruin the tyre !.

 

[TonyC]

Thanks guys. Yes I did wonder that myself. It’s definitely gone in inflated (I would have noticed!) and come out deflated. Wasn’t sure how the TPMS worked. Good thing is I know, so hopefully the tyre can be plugged ok without replacing.

 

[tsedge]

 

[bowfer]

Can’t be right that the wheel needs to be turning, can it?
That’s not TPMS, that’s a more basic system that detects changes in the wheel rotation speed and deduces there must be a puncture (the actual pressures are never displayed)
TPMS should measure pressure even when static, I’ve seen the values change when I’ve pumped the tyres up on various cars with TPMS (our current Evoque etc)
TPMS is crap on the MG, I had individual sensor failure within yards of collecting the car and then complete system failure (where all 4 wheels stuck at 2.5 bar regardless)

 

[TonyC]

Can’t be right that the wheel needs to be turning, can it?
That’s not TPMS, that’s a more basic system that detects changes in the wheel rotation speed and deduces there must be a puncture (the actual pressures are never displayed)
TPMS should measure pressure even when static, I’ve seen the values change when I’ve pumped the tyres up on various cars with TPMS (our current Evoque etc)
TPMS is crap on the MG, I had individual sensor failure within yards of collecting the car and then complete system failure (where all 4 wheels stuck at 2.5 bar regardless)

Thanks for your reply. More investigation required on this!

 

[Alb]

I think the point is the system doesn't wake up until the car is moving.

 

[bowfer]

I think the point is the system doesn't wake up until the car is moving.

Again, I don’t think this is correct.
I’m sure the pressures can be seen to change when the car is static.
Can’t prove it on the 4, seeing as I don’t have one any more and I’m going from memory, but it’s absolutely the case on our Evoque, the pressures change ‘live’
Why wouldn’t they?
They literally measure pressure all the time and as long as the ignition is on the display should change.

 

[Diggsy]

I’ve only ever seen a tyre pressure monitor warning light go off after the car has moved a certain distance, and that was on several previous cars, so those systems didn’t reset or register changes immediately.

Can only assume that similar is at play here

 

[bowfer]

I’ve only ever seen a tyre pressure monitor warning light go off after the car has moved a certain distance, and that was on several previous cars, so those systems didn’t reset or register changes immediately.

Can only assume that similar is at play here

I think you’re confusing TPMS with the older version that didn’t actually display pressures and the first clue you had was some sort of (usually yellow) warning light on the dash.
That’s not TPMS, true TPMS doesn’t need tyre rotation to measure pressure.

 

[TonyC]

I reversed it out of the garage, and then a couple of yards more, to see if anything would change, then drove back into the garage. TPMS not registered, which makes me think it’s the rotational system that’s on the car and not actual pressure measurement. Anyone know where the jacking points are? I’ll check the manual, but if anyone has experience please feel free to comment.

 

[bowfer]

I reversed it out of the garage, and then a couple of yards more, to see if anything would change, then drove back into the garage. TPMS not registered, which makes me think it’s the rotational system that’s on the car and not actual pressure measurement. Anyone know where the jacking points are? I’ll check the manual, but if anyone has experience please feel free to comment.

Needs another owner to confirm, but I’m pretty sure it should register pressures live, no movement needed.
I absolutely know this is the way it works in our Evoque, I don’t see any reason it’s TPMS would differ from another TPMS.
I think peopke here are confusing TPMS with simpler low pressure warning systems.
Perhaps your system is ‘jammed’ like mine was, it displayed the sane pressures no matter what and took the dealer ages to fix.

 

[Alb]

Again, I don’t think this is correct.
I’m sure the pressures can be seen to change when the car is static.
Can’t prove it on the 4, seeing as I don’t have one any more and I’m going from memory, but it’s absolutely the case on our Evoque, the pressures change ‘live’
Why wouldn’t they?
They literally measure pressure all the time and as long as the ignition is on the display should change.

I can't be definitive about the MG4 but it certainly works this way on the MG5.
See my thread on the subject here:

TPMS Anomaly

The car was on charge last night so I powered up and did a quick dashboard check this morning to make sure it had completed successfully. Whilst doing this, I ran through the dash options and my attention was drawn to the TPMS Monitor. You can see from the ambient temperature display (17 Deg C)...

www.mgevs.com

 

[Diggsy]

I think you’re confusing TPMS with the older version that didn’t actually display pressures and the first clue you had was some sort of (usually yellow) warning light on the dash.
That’s not TPMS, true TPMS doesn’t need tyre rotation to measure pressure.

Ah, maybe that’s it. Explains why I didn’t see actual pressure readings on those cars

 

[TonyC]

I reversed it out of the garage, and then a couple of yards more, to see if anything would change, then drove back into the garage. TPMS not registered, which makes me think it’s the rotational system that’s on the car and not actual pressure measurement. Anyone know where the jacking points are? I’ll check the manual, but if anyone has experience please feel free to comment.

I shall do a remote scan tomorrow when the wheel is about 25 miles away from the car and see what it says then…

Needs another owner to confirm, but I’m pretty sure it should register pressures live, no movement needed.
I absolutely know this is the way it works in our Evoque, I don’t see any reason it’s TPMS would differ from another TPMS.
I think peopke here are confusing TPMS with simpler low pressure warning systems.
Perhaps your system is ‘jammed’ like mine was, it displayed the sane pressures no matter what and took the dealer ages to fix.

I must admit I’ve been dubious of the 2.6 bar all round reading. Anyway, the tyre needs fixing first and I’ll worry about the other stuff later ?

 

[Lovemyev]

There are different types of TPMS systems and they work in different ways, of course !.
On the VAG system the TPMS system is linked into the ABS system.
It is constantly monitoring ( in milliseconds) the speeds that each wheel is travelling at and then reports any discrepancies back to the system and then onto the driver, if necessary.
Simply it is able to recognise if one wheel is turning faster than the other wheels / tyres because it has a suspected puncture.
It is clever enough to spot a wheel that is turning faster because it is carrying less air than the other wheels / tyres.
The TPMS system that MG have gone for has a TPMS sensor located in the tyre valve of each wheel and not via the ABS system I believe.
Which system is better is debatable, but I have witnessed BOTH systems and they can report vague / incorrect reports.
I have seen similar issues with the BMW system also !.
So, not all systems are perfect, but going on past experience, the TPMS system on the VAG system, was triggered when it detected a 4 PSI difference in tyre pressure on a suspected punctured tyre.
Like many of these computer generated systems, they sometimes get it wrong !.

 

[tsedge]

People might want to watch the 1 minute video I posted above. It explains that TPMS systems often save their batteries by not transmitting until the wheels are turning above a certain speed.

 

[Tight Git]

Mine has a slow puncture in nearside rear and once the warning comes on and I pump it up, it doesn't clear the warning until I have driven a short distance.

 

[tsedge]

Mine has a slow puncture in nearside rear and once the warning comes on and I pump it up, it doesn't clear the warning until I have driven a short distance.

Exactly as designed.