Tyre Pressure Monitor

[Silverstar]

Since I bought the car every one or two months I get a low tyre pressure warning when starting the car, the last few times it told me the right rear tyre pressure is low. Seems like the right rear tyre is loosing pressure way quicker than the other three (very slow puncture or dodgy valve perhaps) but this morning I got this message:



As you can see this time it does not say which tyre is low just a general message telling me something is wrong. For those of you who have the older tyre pressure monitoring system do you get message telling you which tyre is low? I can't understand why the last few times it specifically said right rear tyre pressure low but this time it doesn't tell me which tyre it is.

 

[Anonymous]

Don't you have the symbology of a little car with 4 green tyres (or one in red)?

 

[enuff_zed]

And when you checked the tyres, was it the right rear low again?

I believe they come on if a tyre loses more than 2psi from what you set the monitor at.
So if it's only lost a little bit, the colder temperatures can cause the pressure to drop below that threshold.

Incidentally, my 335d persistently tells me the right rear is about 3 psi lower than the left, but when I check with a gauge, they are both the same, so there' no guarantee that the sensors are wholly accurate anyway.

 

[Silverstar]

Don't you have the symbology of a little car with 4 green tyres (or one in red)?

The symbology showed all four tyres in yellow and after I corrected the pressure and reset the monitor all four are now showing green.

And when you checked the tyres, was it the right rear low again?

I believe they come on if a tyre loses more than 2psi from what you set the monitor at.
So if it's only lost a little bit, the colder temperatures can cause the pressure to drop below that threshold.

Incidentally, my 335d persistently tells me the right rear is about 3 psi lower than the left, but when I check with a gauge, they are both the same, so there' no guarantee that the sensors are wholly accurate anyway.

The pressures according to the label in the door jamb should be 2.5 bar front and 3.0 bar rear when I checked the right rear was 2.25, left rear 2.85 and the front left 2.45 front right 2.35 if I remember correctly. Whenever I get the warning message in the past and it used to tell me right rear low, and when I checked all tyres were similar to this scenario.

 

[Anonymous]

Don't you have the symbology of a little car with 4 green tyres (or one in red)?

The symbology showed all four tyres in yellow and after I corrected the pressure and reset the monitor all four are now showing green.

And when you checked the tyres, was it the right rear low again?

I believe they come on if a tyre loses more than 2psi from what you set the monitor at.
So if it's only lost a little bit, the colder temperatures can cause the pressure to drop below that threshold.

Incidentally, my 335d persistently tells me the right rear is about 3 psi lower than the left, but when I check with a gauge, they are both the same, so there' no guarantee that the sensors are wholly accurate anyway.

The pressures according to the label in the door jamb should be 2.5 bar front and 3.0 bar rear when I checked the right rear was 2.25, left rear 2.85 and the front left 2.45 front right 2.35 if I remember correctly. Whenever I get the warning message in the past and it used to tell me right rear low, and when I checked all tyres were similar to this scenario.

How old is the car? they , like all sensors deterioate..maybe ones going rogue..

 

[Silverstar]

It's a 2009

 

[Anonymous]

It's a 2009

Life expectancy is predicted at 5-7 years..so...but I'm confused, it sounds like you have TPM not TPMS..TPMS came in around 2014-2015 and the car picture shows actual tyre pressures yours doesn't? just colours?

 

[Silverstar]

It's a 2009

Life expectancy is predicted at 5-7 years..so...but I'm confussed, it sounds like you have TPM not TPMS..TPMS came in around 2014-2015 and the car picture shows actual tyre pressures yours doesn't? just colours?

Yes that's correct it's the older system just shows colours on the tyre not the actual pressures.

 

[Anonymous]

Well, in that case, there are no wheel based sensors..it works by comparing the relative rotation of each of the 4 wheels..so tht's the good news..

Bad news is assuming no actual leaks it may be your reluctor ring!!!

Not a bowel related matter but something like this..

https://www.ukpartsdirect.com/bmw-1-series-rear-abs-reluctor-ring-and-abs-sensor-kit-1.html

These sit on the shafts on each wheel and the ABS/ DSC/TPM all use them..

Apart from that I'm(currently out of ideas)..if it was one of these rings you would expect to see other issues eventually starting liek abs/dsc warnings..

 

[Silverstar]

There are no other errors like ABS DSC etc, I am wondering if the pressure in more than one tyre has fallen below the prescribed limit for the monitor so giving me a general message. Now I have corrected the pressure and reset the monitor I might just let the right rear tyre down to 2.25 bar and knowing that the other 3 are ok, see if it gives a warning displaying right rear tyre low (as I used to get before) rather than a general error message.

 

[Anonymous]

You can try that..another thought is do you have an asymmetric situation such as a badly worn tyre, non matched set etc?

The simpler system you have is a bit crude and needs at least a 20% deflation to detect it....

I can’t remember the legal limits as it varies by country but in my experience it only seems to trigger once the tyre has got a bit ‘squidgy’..ie around the 20 psi type area..

 

[Silverstar]

You can try that..another thought is do you have an asymmetric situation such as a badly worn tyre, non matched set etc?

The simpler system you have is a bit crude and needs at least a 20% deflation to detect it....

I can’t remember the legal limits as it varies by country but in my experience it only seems to trigger once the tyre has got a bit ‘squidgy’..ie around the 20 psi type area..

Tyres are all new purchased around 8 months or 4000 miles ago.