Low pressure tyre warning

[fnegroni]

the threshold on the fronts used to be 2.3 bar and 2.4 for the rears.
The numbers do round up.
And the display is updated only when tyres are rotating, but the warning can be triggered when the tyres are stationary.
I speculate that your tyres are at under 2.5, say 2.45, and they go down to 2.35 overnight and the TPMS is active. Really need to dig out the workshop manual.

 

[Ian Key]

Or just blow them up to 2.6 bar all round, forget about it and enjoy the car.

 

[fnegroni]

Or just blow them up to 2.6 bar all round, forget about it and enjoy the car.

I’d say 37 psi all round, but either will achieve same (37psi is 2.55bar)

remember to put some air in by October November

 

[Rip Van]

I’d say 37 psi all round, but either will achieve same (37psi is 2.55bar)

remember to put some air in by October November

I like 38.?

 

[tsedge]

Just don't get your units confused when inflating, like when I received a brand new Qashqai with tyres at 73psi!

 

[blue232]

I think this also might relate to the monitoring while stationary.
After you took that screenshot, did the warning disappear?

Nope, I drove to the garage (for other reasons) and the warning stayed on the whole journey. Warning came on again when they moved the car as I got the alert on my phone through the app. I’ve had 31 alerts over the last 2 days.

 

[teejayuu]

I've a tyre that probably has a slow puncture. The TPM doesn't activate until the tyre is at 2.1ish. This seems really low?

 

[jammamon]

I've been getting near constant tyre pressure warnings lately for the two rear tyres. I inflated the tyres at the required 2.5 level and it still flags them as low pressure while showing 2.5 on the screen.

It is just me in the car, no passengers, no luggage, so 2.5 is what it says on the door for a half-laden car. Am I missing something here?

 

[DeeKay]

This happened to me too. Now I just inflate tires to 2.7 bar and there are no more warnings.

 

[Tight Git]

There will be a hundred threads just like this in the next few weeks now we are going into autumn and the ambient temperature is dropping...

Just put a bit more air in all of the tyres, as they are just on the threshold of triggering the warning and when it is cold they drop just enough to set the warning off/

 

[jammamon]

Yes, but why a warning if the car measures the pressure at exactly the optimum suggested level? It should warn you at 2.4 or below.

 

[Ian Key]

There is already a long thread on this subject

Low pressure tyre warning

Last night on my way home I suddenly got a low pressure tyre warning. When I called up the tyre pressure screen all the tyres were at 2.4 or 2.5 BAR, including the one that is supposedly low. When I scanned the car with the app this morning, same thing. Low pressure warning but all tyres...

www.mgevs.com

 

[AlexC]

Apparently tyres lose up to 1psi per month (we need settings option to show in PSI rather than bar) so the TPMS seems quite accurate, although I questioned it as above when it triggered just after I got car, but has dropped from 2.5 -> 2.4bar. So we should all check monthly.

 

[Kithmo]

Yes, but why a warning if the car measures the pressure at exactly the optimum suggested level? It should warn you at 2.4 or below.

Because reading the pressures in bar is probably not as accurate as the TPMS sensor, 2.5 bar could be anything between 2.45 to 2.54. If it read in KPa it would show this, e.g 2.45 bar = 245 kPa.
I agree the threshold should be greater though, the last Toyota Prius I had didn't register a loss until it was 10 psi under (0.7 bar).

 

[siteguru]

From what I've seen (of people posting who have kPa readings) the measurement seems to increment in 4 kPa (0.04 Bar) steps. So (e.g.):

250 kPa
254
258
262 etc.

 

[AlexC]

From what I've seen (of people posting who have kPa readings) the measurement seems to increment in 4 kPa (0.04 Bar) steps. So (e.g.):

250 kPa
254
258
262 etc.

I’m going to request setting option to show in PSI, as that’s what we use in UK

 

[fnegroni]

I really need to dig out the workshop manual which describes how the TPMS works on the MG4 because I think what people are seeing are warnings generated when the car is stationary and the tyre pressure has fluctuated too much.
If your tyres were set to 2.45 bar at midday, chances are over the next few days your tyres at night will go to below 2.3 quickly once the sun sets.

I use a tyre inflation pressure gauge which gives me the same result (to the second decimal place) as the TPMS gauges in each tyre. It’s an AstroAI unit.
So I know why sometimes it shows 2.7 bar on three tyres but 2.6 on one of them and yet they were all pretty much identical when I set them when cold at 2.55 bar (37psi)

I also adjust the tyre pressure when humidity is low, and the sun isn’t shining directly on the tyres. Preferably before sunrise or after sunset

 

[fnegroni]

 

[fnegroni]

If anyone gets warning, please post a picture of it: there’s a page on the right hand side of the drivers instrument cluster you must scroll through with the steering wheel right joystick to uncover the actual warning: it’s on the page with a shield symbol but you must scroll down to reveal it

 

[AlexC]

Before (warning) & After photos (cleared). Not triggered today, 18deg ambient.