W205 C63 - is there a brake sensor warning light?

[BJC]

Hi,

When I last got my 2019 W205 C63 serviced, they said the pads (I assume the rears from traction control and using adaptive cruise control) were near a warning marker.

I've now started to notice some brake squeal, and I'm wondering if that's the brake pads hitting a certain wear point and saying "please change me" in an audible fashion.

I've looked through the manual and some online videos and pictures, and older C classes or ones without the digital dashboard suggest I'd get a on screen warning or icon to saybthe pads need changing. I've not spotted anything like that on mine yet.

Is that assumption of mine correct?

Seeing the pads themselves is hard because of the alloys I have, plus I know my limits and I'm not a mechanic.

I know the car is due for its third service in ~60 days, but I want to make sure I don't ruin the discs if the pads are indeed low (i.e. if they need doing now, I'll get them done now).

Thanks in advance, Ben

 

[sgregory124]

I am in the same situation. Was advised my rears are 60% done, I enquired if there would be a dash warning light when they actually needed doing, to which I was told 'yes'. So i'm leaving mine until the car tells me they need doing.

Also, I don't think you can count the squeal as any indication of wear, my brakes have squealed since the day I got the car in 2020 (slow speed braking only - high speed and 'spirited' braking is usually silent) , i'm just used to it now. The noise i'd be more inclined to listen out for would be grinding or the like, like metal on metal (caliper on disc!).

 

[Spider10]

+1 for the above mine also squeal under slow braking

 

[hedgehogsdad]

If you look on Euro Car Parts or the like at the parts, they also sell wear indicators, which suggests that there would be a light. I'm in the same boat with my fronts ....

 

[Iggu]

Yeah a light does come on. Wait for that to happen and don’t do what the dealer tells you - I got around 4,000 miles more out of mine (before the light came on) after the dealer told me to replace them. Even after the light comes on you get 1,000 miles or so.
Mine also squeal - it’s a “feature” of the car.

 

[Muckypaps]

Relying on the wear indicator illuminating is not without risk.
It only monitors one pad across the rear axle instead of all four pads. You have to hope the three other pads don’t wear out before the one with the sensor.
It could mean the difference between new pads, or new discs and pads.

 

[sgregory124]

Relying on the wear indicator illuminating is not without risk.
It only monitors one pad across the rear axle instead of all four pads. You have to hope the three other pads don’t wear out before the one with the sensor.
It could mean the difference between new pads, or new discs and pads.

Don't know about the OP but I know my discs and pads both need doing, part of the reason i'm waiting - may as well get my money's worth out of the existing pair on the back, given the cost of them.

 

[BJC]

Thanks for the info all, it is slightly reassuring there is a sensor. Using one sensor for different corners is slightly bemusing to me.

It's definitely a squeal and not metal grinding noise, and I may have inadvertently exasperated it this past week by doing very short journeys and being paranoid of braking too much (maybe it needs a hard brake to clear muck off etc.)

When the time comes, I hope its just pads.

Thanks again all.

 

[f17ant]

Yes there is a light that comes on and you will probably have some miles left. BUT if the light comes on usually you will need to change the sensor too,

If you do it before you will save the sensor

 

[BJC]

Yes there is a light that comes on and you will probably have some miles left. BUT if the light comes on usually you will need to change the sensor too,

If you do it before you will save the sensor

Thanks for this... if that's the case, I'll make some calls next week to get her booked in for some TLC.

 

[Steve84N]

The sensor is less than a tenner...

 

[f17ant]

The sensor is less than a tenner...

True… but thought would be better to mention it anyways

 

[BJC]

The sensor is less than a tenner...

OK, now I don't care so much

 

[Steve84N]

It's wise to replace the sensor even if it doesn't trip so just use it.

 

[Petrol Pete]

Waiting for the light to come on is a bit of a gamble unless you know 100% that the sensor is actually there and has not been removed or bridged out.

It happens.

And (as said) not all of the pads have sensors in many cases its just one front and one rear pad that is 'wired up'

 

[W1ghty]

My dealer told me my front discs needed changing at 40k miles , I did them at 100k when they started to look a bit tired .

 

[sgregory124]

Waiting for the light to come on is a bit of a gamble unless you know 100% that the sensor is actually there and has not been removed or bridged out.

It happens.

And (as said) not all of the pads have sensors in many cases its just one front and one rear pad that is 'wired up'

If there's only one sensor per axle, that does beg the question, what is the point in having a light to 'warn' you of excessively worn pads in the first place, if the first pad to go has no sensor at all?

By that reckoning, you could end up in a crash because you weren't aware they were shagged....

 

[Spider10]

Most car's only have 1 sensor per axle nowadays

 

[Petrol Pete]

If there's only one sensor per axle, that does beg the question, what is the point in having a light to 'warn' you of excessively worn pads in the first place, if the first pad to go has no sensor at all?

By that reckoning, you could end up in a crash because you weren't aware they were shagged....

Don't ask me . I didn't design the (very common) system.

 

[Steve84N]

The sensor trips when there's a few mm left so even with uneven wear it's very rare not to trip the sensor before the pads are unsafe.