Brake pad wear sensor - needs to be changed?

[markorak]

Hello all!

Today I got my wheels switched from the winter-set to the summer one.

I noticed that the rear discs and pads are as good as dead. However, the service-screen shows that both front and rear pads need to be changed in about 3000km. Front ones look almost new, so they are staying in.
Since I am the second owner, I don't really know the history about when these got changed last.

However, the wear is not my concern. What I am wondering is how these brake pad wear sensors work and are they sending any information to the info-system?

Correct me If I am wrong, but I think the amount of kilometers left in the info-screen is just a value set by BMW at the last brake-pad change?

The Brake-pad-wear sensors themselves only trigger when the pad is really dead, right?

And last but not least, do I need to order these sensors as well when changing the discs and pads? From what I have seen they are not molded inside the pads?

I appreciate any answer,

Cheers guys.

PS: I got a 15' X5 40e

[stocktree]

There is two wires going to a sensor mounted on one of the pads on the rear. When the pad wears, and the sensor touches the rotor, the light to change the pads gets triggered.

[markorak]

Originally Posted by stocktree

There is two wires going to a sensor mounted on one of the pads on the rear. When the pad wears, and the sensor touches the rotor, the light to change the pads gets triggered.

Okay so If I change the pads before this is triggered, I do not need a new sensor? But If it does trigger, then I do, correct?

Also is there only one sensor per axle or is there one on each disc?

[1004ron]

There's only one rear pad wear sensor and it's on the Right rear.

If it hasn't worn through the plastic housing of the sensor you could re-use it, but the small retaining spring is unlikely to be in good condition.

The sensors are very cheap, so if I was installing new pads it would be with new sensors - just a little more work getting to the connector behind the wheel liner.

[markorak]

Originally Posted by 1004ron

There's only one rear pad wear sensor and it's on the Right rear.

If it hasn't worn through the plastic housing of the sensor you could re-use it, but the small retaining spring is unlikely to be in good condition.

The sensors are very cheap, so if I was installing new pads it would be with new sensors - just a little more work getting to the connector behind the wheel liner.

I see, amazing. Thanks!

Is there any specific disc/pad/sensor combo to be recommended or does that come down to personal preference?
I was thinking coated Brembo discs/ Brembo sensor and Brembo pads. However, the pads don't come with "Accessories", which I think means I need to get the large clips. - Mine are rusted anyway...

The reason I am asking is that I definitely want to order the parts myself and have them fit. (I got no space to do it myself)
The whole rear brembo set will cost me 160,- Euro in parts compared to 400,- if I order it via him, let alone BMW

[1004ron]

Originally Posted by markorak

Is there any specific disc/pad/sensor combo to be recommended

No.

https://f15.bimmerpost.com/forums/sh...17&postcount=3

[markorak]

Originally Posted by 1004ron

No.

https://f15.bimmerpost.com/forums/sh...17&postcount=3

Thanks!

[Qsilver7]

Brake sensor locations:

• rear RIGHT wheel
• front LEFT wheel

[tlaspec]

Check to ensure your inners are not worn, I had case due to winter salt corrosion my outer pad had 10mm while inners was worn down to 3mm triggering sensor.

If pad is all good there is setting in ista in same menu where you reset oil can reset brake pad life as well,

[Tomcat_F15_STL]

No real reason to replace the sensor if it is not worn through.

[markorak]

Originally Posted by tlaspec

Check to ensure your inners are not worn, I had case due to winter salt corrosion my outer pad had 10mm while inners was worn down to 3mm triggering sensor.

If pad is all good there is setting in ista in same menu where you reset oil can reset brake pad life as well,

Good one! Will check this when I get the rear changed. Thanks!

Originally Posted by Qsilver7

Brake sensor locations:

• rear RIGHT wheel
• front LEFT wheel

Also appreciate this, very good info.

Thanks also to everyone

[CatalinP]

Originally Posted by Tomcat_F15_STL

No real reason to replace the sensor if it is not worn through.

Actually, there is. The sensor is secured to the brake pad using a metal clip. When you remove the sensor to replace the brake pad, that clip deforms and the sensor becomes loose, making it useless...

[tlow98]

Originally Posted by CatalinP

Actually, there is. The sensor is secured to the brake pad using a metal clip. When you remove the sensor to replace the brake pad, that clip deforms and the sensor becomes loose, making it useless...

And prone to falling out and getting ripped apart, which sets off the light and you have to go back in there. Ask me how I know :-/

Now I replace it every time bc I dislike doing double work more than spending the $10 * 2.