TPMS

[steve333]

Hi all,strange one regarding TPMS ,reset after checking/adjusting pressures last Friday and whilst driving yesterday message popped up check/adjust tyre pressures,drove to a garage and checked them but they were all correct so restarted monitor and all ok since-any ideas?(2010 cls 350cdi auto)

 

[OneForTheRoad]

Cold ?

 

[steve333]

Cold ?

Don’t think so,was around 10 degrees yesterday but colder when I checked/topped up a reset last Friday?

 

[whitenemesis]

Always check/adjust tyre pressures when the tyres are cold i.e. first thing in the morning, before using the car.

 

[markjay]

If you have the full TPMS system, then you may have a TPMS sensor that is failing (possibly internal battery issue).

If you have the ESP-based TPMS system, then make sure it is reset from the instrument panel once the tyre pressure has been corrected. Failing that, there may be an issue with one of the ABS wheel sensors.

 

[rf065]

I suspect you never reset the monitors when you adjusted the pressures the first time?

 

[steve333]

Thanks for the replies-just to clarify,tyres were checked from cold 1 mile from home and TPMS reset via the instrument panel,not sure which system I have but it’s the one that doesn’t show individual tyre pressures which I’ve had on other mb’s,as an after thought I pressure washed the wheels the day before adjusting pressures-would that have an affect on the sensors I wonder?

 

[rf065]

You don't have pressure sensors as such, it uses the ABS system to measure the wheel speed instead.

 

[CaptainChaos]

I had a BMW which used the wheel circumference/ABS method. If I hit a pothole or an undulation in a certain way it could trigger it. Happened very rarely but presumably the sensor just gets out of synch for a split second. Maybe that's what has happened here.

 

[steve333]

I had a BMW which used the wheel circumference/ABS method. If I hit a pothole or an undulation in a certain way it could trigger it. Happened very rarely but presumably the sensor just gets out of synch for a split second. Maybe that's what has happened here.

Sounds most likely-we did hit a bad piece of road surface about 30 minutes prior to the check tyre pressures message...

 

[markjay]

Thanks for the replies-just to clarify,tyres were checked from cold 1 mile from home and TPMS reset via the instrument panel,not sure which system I have but it’s the one that doesn’t show individual tyre pressures which I’ve had on other mb’s,as an after thought I pressure washed the wheels the day before adjusting pressures-would that have an affect on the sensors I wonder?

If you have the ESP/ABS-based TPMS system, then the temperature of the tyres is irrelevant, as are the actual inflation pressures.

All the system monitors is that the wheel's rotational speed is the same as the other three wheels.

As long as you have set the tyre pressure to be the same on all tyres, then reset the TPMS from the instrument cluster menu, then the actual pressure values or the tyre temperatures do not matter.

And it is unlikely that a pot hole activated the TPMS warning some 30 minutes after impact (unless it actually caused pressure loss).

I would correct the pressure on all tires then reset the TPMS monitor, and see what happens next.

 

[steve333]

If you have the ESP/ABS-based TPMS system, then the temperature of the tyres is irrelevant, as are the actual inflation pressures.

All the system monitors is that the wheel's rotational speed is the same as the other three wheels.

As long as you have set the tyre pressure to be the same on all tyres, then reset the TPMS from the instrument cluster menu, then the actual pressure values or the tyre temperatures do not matter.

And it is unlikely that a pot hole activated the TPMS warning some 30 minutes after impact (unless it actually caused pressure loss).

I would correct the pressure on all tires then reset the TPMS monitor, and see what happens next.

Hi Mark,pressures were checked again after message popped up and didn’t need adjusting so reset TPMS and all ok since-strange.

 

[Gbrowncls55]

Isn't that system TPWS. TYRE PRESSURE WARNING SYSTEM?

 

[Deleted member 126251]

You could do what my wife does and just ignore it!

 

[rf065]

Hi Mark,pressures were checked again after message popped up and didn’t need adjusting so reset TPMS and all ok since-strange.

Thinking back, I'm sure my CLK did the same a couple of times. I wouldn't worry about it.

 

[CaptainChaos]

And it is unlikely that a pot hole activated the TPMS warning some 30 minutes after impact (unless it actually caused pressure loss).

Indeed. The situation I was describing was an instant reaction. In fact there was one stretch of road which triggered it each time. I can only think the tyres deformed slightly as they hit the ridge in the road and momentarily "read" as being under size.

 

[whitenemesis]

Indeed. The situation I was describing was an instant reaction. In fact there was one stretch of road which triggered it each time. I can only think the tyres deformed slightly as they hit the ridge in the road and momentarily "read" as being under size.

I'd doubt it as the ABS based warning system only reacts to gross changes, as in approx 25+% difference in rotational speed. This obviously must be calculated over a significant number of revolutions and in comparison with the other wheels. An 'instantaneous' event is very unlikely to trigger a warning.
A more likely reason would be a random digital/electrical 'glitch'. Why you would repeatedly experience such an event along a particular stretch of road is curious..

 

[Petrol Pete]

Or the shock strut is old and the wheel left the road on rebound and it's rotation slowed momentarily ? not sure the system is that precise though.

 

[dafrog]

Thinking back, I'm sure my CLK did the same a couple of times. I wouldn't worry about it.

My CLK has done it twice recently and pressure ok. Can't find the reset now so I'll leave it til next service.