Low pressure tyre warning

[Cherishwit]

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 are showing normal pressure.

Do I believe the pressure readings and assume this is a false alarm? How do I clear the warning?

Bowfer mentioned having a similar problem last year but as I haven't seen a thread on this in five months I thought I'd start again.

I had the same thing and rang the Service Garage, they said not to worry as it was down to the drop in temperature and was probably just borderline. My car was due for it's service anyway and they have checked it all and is now fine.

 

[JonnyG]

I'd just pump them all up to 2.55bar first thing on a cold morning. Check pressures again using your pump / gauge to be doubly sure and then drive a few miles. The TPMS should then start to recognise the slightly higher and correct pressures and the warnings disappear for good (or until even colder weather hits you !)

 

[siteguru]

I set my digital compressor to 37.5 psi, to account for the small pressure loss inevitable as you disconnect the compressor hose. That way I know I'll have at least 37 psi in the tyre (at whatever the ambient temperature happens to be).

 

[goose]

A quick note to thank fnegroni MG4 SE SR gen1 for all the help given on the tyre pressures and sensors issue I had. A really good explanation of how the system works and why sometimes the warning can appear when it looks very much like tyre pressure is the same on each wheel. Well, I took your advice and pumped the pressure up to 2.5Bar and then rechecked each tyre in turn.

It took a little while for the sensor to catch up, but after a few miles of driving, the warning disappeared and the pressure shown on each tyre was exactly the same and steady at 2.5 (went up to 2.6 all round when they warmed up). So my sincere thanks and I guess it is never too late to learn something new.
Thanks again and Happy motoring!!
By the way, I just love the car and I am slowly getting to grips with the range of electronic gizmos that are present.

 

[Rolfe]

That's what I did, and even though the weather has got a lot colder, and the temperature is fluctuating, I've never had another alert.

Glad you love your car!

 

[KH11]

Just had to top my tyres up on Monday after returning from holiday Sunday as I had got the left rear tyre warning. My tyre inflator doesn’t show bar it shows PSI but after reading on the forum what the conversion was I decided to top them all up to 39psi and just went on a short run and the tyre pressure screen soon caught up and had no problem since

 

[siteguru]

37 psi (2.55 bar) is the specified pressure.

 

[KH11]

37 psi (2.55 bar) is the specified pressure.

I think that depends on what you are loading the car with and how many people

 

[siteguru]

Of course ... as with ANY car.

But that's the default starting point.

 

[Diggsy]

Yep, I think the manual advises inflating to 2.5 bar when the tyres are cold. That’s the bit most people will overlook, and simply inflate when they get to the service station, by which point tyres will likely be anything but cold

 

[tsedge]

There is no such thing as the "right" tyre pressure - it all depends on which tradeoffs you want to optimise for:

• right for wear/longevity
• right for comfort
• right for handling/grip
• right for efficiency/range
• etc...

Usually optimising for one means a compromise on the other factors - eg more comfortable ride with greater wear.

While you should not depart too much from manufacturer's recommendations you should be aware that the tyres will increase pressure significantly as they warm up - this is something people exploit on tracks by starting with under-inflated tyres so that they will be at the right pressure when warmed up rather than too high.

So.. don't obsess too much about the value, choose something that works for you.

 

[ukslim]

This is all too much fuss for most people. It's easy:

You WILL get a pressure warning when the weather turns colder. This is expected.

• Go to a garage with an air machine. e.g. Tesco. Set it to 2.5 bar.
• Go round the car taking off all the valve caps.
• Put 50p in the machine
• Stick the wand on the valves one by one, until the machine beeps
• Put the valve caps back on
• Get on with your life for another 3 months or more

Yeah, there's a pump in the boot. But it's fiddly and weak and the gauge isn't very accurate. You might use it to inflate after a run-flat temporary repair, but for routine inflations, pay the 50p, it makes it so easy.

 

[Rolfe]

I have a foot pump I bought to inflate my bicycle tyres. To do that I practically have to jump up and down on the pump, because the bike tyres need to be inflated to over 50 psi. Using the same pump to put a little air in car tyres is trivial by comparison.

 

[siteguru]

I have my own digital compressor, so the one in the car is unlikely to ever get used - even in the event of a puncture. (I also have a tar string repair kit). This compressor seems quite accurate.

 

[Diggsy]

This is all too much fuss for most people. It's easy:

You WILL get a pressure warning when the weather turns colder. This is expected.

• Go to a garage with an air machine. e.g. Tesco. Set it to 2.5 bar.
• Go round the car taking off all the valve caps.
• Put 50p in the machine
• Stick the wand on the valves one by one, until the machine beeps
• Put the valve caps back on
• Get on with your life for another 3 months or more

Yeah, there's a pump in the boot. But it's fiddly and weak and the gauge isn't very accurate. You might use it to inflate after a run-flat temporary repair, but for routine inflations, pay the 50p, it makes it so easy.

I did this before, pretty much exactly as you described. Drove less than a mile and watched all the readings plummet to below 2 bar…1.9 I think they all stopped at.

Turned out the machine at the garage was miles out of calibration, so I ended up having to inflate them all with the box in the boot…royal pain in the bum

 

[tsedge]

I did this before, pretty much exactly as you described. Drove less than a mile and watched all the readings plummet to below 2 bar…1.9 I think they all stopped at.

Turned out the machine at the garage was miles out of calibration, so I ended up having to inflate them all with the box in the boot…royal pain in the bum

That's why it pays to carry a digital automatic inflator. If you buy a decent one it will be accurate and will last.

 

[Deleted member 14300]

Back left is now triggering an alarm on screen. Came on yesterday afternoon. Went off this morning and then came back on this afternoon. I'm going with the car ready to drive attach the pump to it and use the screen to tell me the bar pressure. It needn't start this lol. I've got every other warning on now.

 

[Diggsy]

That's why it pays to carry a digital automatic inflator. If you buy a decent one it will be accurate and will last.

Must do this to be honest. Don’t think I’ll go back to relying on garages again anytime soon!

 

[Rolfe]

Back left is now triggering an alarm on screen. Came on yesterday afternoon. Went off this morning and then came back on this afternoon. I'm going with the car ready to drive attach the pump to it and use the screen to tell me the bar pressure. It needn't start this lol. I've got every other warning on now.

I'm not sure the screen will tell you the bar pressure in real time.

 

[siteguru]

It won't.