TPMS - Fault

[NJP10]

Hi Guys

I’ve been having the TPMS warning light pop up only on the motorways never on local driving and not always straight away, it always seems to be at half way point of the journey. When I do check the tyre pressure at the service station they seem to be fine maybe 1psi out but that’s probably due to different machines being calibrated I assume. The strange thing is I never seem to get the fault message on the return journey! I always check the pressure before leaving maybe the night before or on the day. 

[Steve Q]

Most likely the battery in one of the sensors is failing. Alternatively you could get a diagnostic check to see if any fault codes flag up 

[NJP10]

Hi Steve thanks for getting back to me, I was thinking that also, but it’s baffling why it only goes off on the motorways never on the roads🤔

[Steve Q]

That is an odd one. I'd definitely suspect battery. I'm assuming it's just one sensor? 

[cliffcoggin]

1 hour ago, NJP10 said:

 but it’s baffling why it only goes off on the motorways never on the roads🤔

Motorway journeys are faster than other roads so the tyres get hotter and their pressures higher. Is it possuble that the TPMS can warn of high pressure as well as low?

[NJP10]

1 hour ago, Steve Q said:

That is an odd one. I'd definitely suspect battery. I'm assuming it's just one sensor? 

No idea doesn’t indicate, I’ll get it on a diagnostic machine and see what it comes up with 👍🏽

[Sid2020]

Does your vehicle display the psi of your tyres or is it passive system that warns of pressure loss but does not give a reading, passive systems do not have a sensor in the wheel instead they rely on the rotational speed of the wheel, a flat tyre is a smaller rotating mass so must rotate more to maintain same speed as a inflated tyre, system has been in use for years in bmw’s and does not like tyres with different tread depths, a very clever system using crazy calculations 

[NJP10]

2 hours ago, Sid2020 said:

Does your vehicle display the psi of your tyres or is it passive system that warns of pressure loss but does not give a reading, passive systems do not have a sensor in the wheel instead they rely on the rotational speed of the wheel, a flat tyre is a smaller rotating mass so must rotate more to maintain same speed as a inflated tyre, system has been in use for years in bmw’s and does not like tyres with different tread depths, a very clever system using crazy calculations 

6 hours ago, Steve Q said:

That is an odd one. I'd definitely suspect battery. I'm assuming it's just one sensor? 

No idea doesn’t indicate, I’ll get it on a diagnostic machine and see what it comes up with 👍🏽

Hi Sid2020, No it doesn’t display the PSi readings therefore it must be a passive system. A couple of months ago I had the new tyres fitted on the front, and the old pair went on the rear, which probably has uneven tread depth on them, therefore causing the TPMS fault to occur just on high speed travels, that makes sense now hopefully 🤞🏽

[NJP10]

Hi Sid2020, No it doesn’t display the PSi readings therefore it must be a passive system. A couple of months ago I had the new tyres fitted on the front, and the old pair went on the rear, which probably has uneven tread depth on them, therefore causing the TPMS fault to occur just on high speed travels, that makes sense now hopefully 🤞🏽

[Sid2020]

Just make sure you reset the system in the mmi everytime you change the tyre pressures but yes your right the rear will now rotate ever so slightly more then the front at high speed on a decent drive , the system is very clever as takes readings from the steering angle sensor to compensate for for the differential in front wheel turning rotation. 

[cliffcoggin]

11 hours ago, NJP10 said:

 A couple of months ago I had the new tyres fitted on the front, and the old pair went on the rear, which probably has uneven tread depth on them, therefore causing the TPMS fault to occur just on high speed travels, that makes sense now hopefully

A shame you did not mention that earlier. Whenever you swap wheels or change the pressures the TPMS needs to be recalibrated.

[NJP10]

I didn’t reset the MMI when the tyres were fitted but I always reset it after checking the tyre pressure. Well that resolved this issue, I have a second issue with regards to my rear spoiler fault, do I start a new topic or carry on with this thread?
 

[cliffcoggin]

37 minutes ago, NJP10 said:

 do I start a new topic or carry on with this thread?
 

New topic please. I am locking this one.