C63 Tyre Pressure monitoring

[RhysC63?]

Does anyone know how this works and at what psi does it trigger a warning? I was wondering if it's better to check with a manual pressure gague on a regular basis rather than rely on the gizmo?

Anyone who mentions 600psi will get a lump of coal from santa this year

 

[steve333]

Does anyone know how this works and at what psi does it trigger a warning? I was wondering if it's better to check with a manual pressure gague on a regular basis rather than rely on the gizmo?

Anyone who mentions 600psi will get a lump of coal from santa this year

I,ve found around 4psi up or down triggers the tyre pressure monitor warning,found this out by accident after having new rear tyres & the fitter putting the wrong pressures in them,i always check my tyre pressures weekly with a gauge(when cold),gives optimum fuel economy too(if you can call it that in a petrol v8).

 

[Rashman]

As Steve said, I believe it is triggered after a noticable change in pressure.

 

[Deleted member 37751]

600 psi.
















I'd love a lump of coal for Christmas...

 

[Paul/]

As the others have said, there's a fair margin allowed- I assume this is necessary as otherwise inclines might trigger it (I learned how significant the otherwise imperceptible slope on my drive is when, using the on-board pressure display on the CLS, I got my pressures exactly right on the drive then checked them again once I'd parked on the road- took a while to realise why they were out again).

 

[Deleted member 65149]

As Steve said, I believe it is triggered after a noticable change in pressure.

From the manual:

While the vehicle is in motion, the tyre pressure loss warning system monitors the set tyre pressure using the rotational speed of the wheels. This enables the system to detect significant pressure loss in a tyre. If the speed of rotation of a wheel changes as a result of a loss of pressure, a corresponding warning message will appear in the multifunction display.

Just how "significant" the pressure change is I don't know, but mine hasn't reacted to 5psi either way. Certainly don't rely on it for pressure checks because:

The tyre pressure loss warning system does not replace the need to regularly check your vehicle's tyre pressures, since an even loss of pressure on several tyres at the same time cannot be detected by the tyre pressure loss warning system.

Also bear in mind :

The tyre pressure monitor is not able to warn you of a sudden loss of pressure, e.g. if the tyre is penetrated by a foreign object.

 

[Simon_M]

The warning about multiple tyres is worth noting. If all 4 tyres drop by roughly the same amount no warning will fire. If all 4 of your tyres are at 15psi it will not fire.

It uses the ABS sensors so does not work on pressure - no substitute for setting and checking manually.

 

[Dieselman]

Just how "significant" the pressure change is I don't know, but mine hasn't reacted to 5psi either way. Certainly don't rely on it for pressure checks because:
Quote:
The tyre pressure loss warning system does not replace the need to regularly check your vehicle's tyre pressures, since an even loss of pressure on several tyres at the same time cannot be detected by the tyre pressure loss warning system.
Also bear in mind :
Quote:
The tyre pressure monitor is not able to warn you of a sudden loss of pressure, e.g. if the tyre is penetrated by a foreign object.

That all begs a question of how effective it really is.

It doesn't detect rapid pressure differences and it doesn't detect variations over a period of time of at least 5psi...so if one checks the pressures regularly anyway, as advised, the TPM doesn't serve any purpose.

 

[Deleted member 65149]

That all begs a question of how effective it really is.

It doesn't detect rapid pressure differences and it doesn't detect variations over a period of time of at least 5psi...so if one checks the pressures regularly anyway, as advised, the TPM doesn't serve any purpose.

Perhaps if I'd tried the pressure change over a day or so it may have been picked up. It might have thought my system trial by letting the air escape within less than a minute was a "sudden loss of pressure" caused by a "significant" puncture. Sorry guys, it's going to have to get a lot warmer outside for me to carry out a slower test!

 

[Simon_M]

Remember it is the ABS sensors working so the car has to be rolling to pickup a change in pressure.

Why not just accept that it works until you get a puncture?

 

[developer]

I use my Highline TPM to quickly check invividual pressures are in the right area (according to the dash display) if something feels a bit odd, however, I always accurately check and set with a good quality gauge and footpump.

 

[Rashman]

......by a foreign object.

Goddamn Frenchies

 

[Fady]

Remember it is the ABS sensors working so the car has to be rolling to pickup a change in pressure.

Why not just accept that it works until you get a puncture?

I'm with you. Checked the pressures and then picked up a nail a day or so later. This resulted in a slow puncture which I was alerted to whenever I started the car. I did a couple of short journeys with a footpump in the boot until I was able to sort it out and I was warned whenever it had deflated.

 

[Paul/]

That all begs a question of how effective it really is.

Indeed. Interestingly, checking the W219 user manual info on the version of the system that displays all 4 tyre pressures on the multifunction display:

"

​

​

​

​

​

​

Possible differences between the readings​

of a tire pressure gauge of an air hose,

e.g. gas station equipment, and the vehicle’s
control system can occur. Usually the
readings issued by the control system are more precise."​

​

​

It certainly drove me nuts trying to reconcile foot pump readings on the drive then running around until the onboard display updated, only to find a discrepancy. I assume because the footpump measured with the vehicle on a slight slope, whereas the TPMS factors that out by measuring on the run. The problem went when I used the footpump on a flat bit of road.

 

[Pitts Pilot]

I don't get any readings at all since fitting MB 17" wheels with winter tyres, (replacing 19" AMG's), although the dash message does initially say "Drive for a while", then it declares "Pressures not available, wheel sensors not fitted, you fool".

So do I have to re-calibrate something?

The fact that I check the pressures on a weekly basis, means I'm not too bothered, but I think the "Sensors not fitted" bit must be wrong?

I thought air pressure was measured by monitoring individual wheel rotational speeds, using the ABS sensors?

Thanks

.

 

[redbaron]

There are two version - the "better" one give you individual wheel pressures and requires sensors. The basic std fit one merely uses ABS sensors to monitor wheel roataion/ circumference differences.

I have a spare set of CLS/E/S sensors from when I had my 221....

 

[developer]

Highline TPM (four declared pressures on the dash display) have tyre valves like this:

and from the inside, like this:

 

[cjhaz69]

I've just had both rear tyres replaced & now the the red warning "check tyre pressure" is on my dash!

 

[steve333]

I've just had both rear tyres replaced & now the the red warning "check tyre pressure" is on my dash!

Have you checked the pressures in them-is it the same as before they we're replaced?

 

[Rashman]

If you are sure that nothing is amiss, it may just be picking up a difference in pressure in your new tyres.

You can reset the tyre pressure monitoring system and I'll be sorted.