I hope someone can help me out with this issue

on my X3 f25, Rear brake pad warning light was ON meaning the sensor was tripped. I drove for ~150 miles before getting chance to take the car to mechanic.

He changed both front and rear brake pads and also claims to have changed the rear brake pad sensor. However, he was unable to reset the warning light. He just told me drive for a while and bring the car again.

At home I used ISTA software to do CBS reset for rear pad warning light 2-3 times. However, it failed every single time. I also tried to clear fault memory multiple times before doing CBS reset but the this error (fault code 480A12) doesn't clear either.

I have also tried with parking brake off as others have suggested online. What else can I try?

I am beginning to think that the mechanic hasn't changed the sensor even though I gave him brand new cable. Any idea how can I check that before i take the car back to him

Most likely either the sensor hasnt been changed or the new one poor quality or not plugged fully home where it joins the harness which can be an issue, only way to know is get wheel off and have a look at it all.

In a pinch i cut the sensor off, strip back the 2 wires inside and twist together then tape/heatshrink up, never have sensor issue again but of course you or garage needs to monitor pad life visually, CBS will give you a guide though.

If the warning was attempted reset on triggered or low quality/not plugged in sensor ive heard it can then be tricky to get the warning to clear, ive not had this myself though.

Good luck!

thetyrant wrote

Most likely either the sensor hasnt been changed or the new one poor quality or not plugged fully home where it joins the harness which can be an issue, only way to know is get wheel off and have a look at it all.

In a pinch i cut the sensor off, strip back the 2 wires inside and twist together then tape/heatshrink up, never have sensor issue again but of course you or garage needs to monitor pad life visually, CBS will give you a guide though.

If the warning was attempted reset on triggered or low quality/not plugged in sensor ive heard it can then be tricky to get the warning to clear, ive not had this myself though.

Good luck!

Thanks for your answer.
Though I can't remove the wheel, I used a led torch, I have noticed that the sensor cable at the front looks new while the one at the back still looks old. So most likely, he didn't even bother checking fitment and just put the cable at the front wheel. Now I have to buy a new one and get it changed for Rear wheel.


Are we supposed to change the sensor cables along with brake pads even if they haven't tripped?

t4ure4n wrote

Thanks for your answer.
Though I can't remove the wheel, I used a led torch, I have noticed that the sensor cable at the front looks new while the one at the back still looks old. So most likely, he didn't even bother checking fitment and just put the cable at the front wheel. Now I have to buy a new one and get it changed for Rear wheel.


Are we supposed to change the sensor cables along with brake pads even if they haven't tripped?

It's generally a good practice to replace the sensor when pads are changed out. On the 'reset', make sure you do not have 'auto-hold' turned on, keep your foot off the brake pedal and as you mentioned disengage the parking brake.

Wgosma wrote

It's generally a good practice to replace the sensor when pads are changed out. On the 'reset', make sure you do not have 'auto-hold' turned on, keep your foot off the brake pedal and as you mentioned disengage the parking brake.

Got it. I will keep this in mind for the next time.

Time for a new mechanic.

t4ure4n wrote

Are we supposed to change the sensor cables along with brake pads even if they haven't tripped?

If the sensor never touched the rotor, and the wire is in good condition, you can reuse it. I've reused the sensor many times since I typically change the pads prior to the sensor being tripped, but they're cheap enough to replace if you want.

It's a known "issue" for the F25. I've been reading about this same issue for years now. I even had this problem myself. I believe I cut the wire from the old sensor and shorted them out. Plugged it in and reset it via the stalk and then reset it using Protool. Then I plugged in the new sensor and reset it again I believe.
I did it last year so I don't remember perfectly. But I had to some trial and error.

Brandoch wrote

It's a known "issue" for the F25. I've been reading about this same issue for years now. I even had this problem myself. I believe I cut the wire from the old sensor and shorted them out. Plugged it in and reset it via the stalk and then reset it using Protool. Then I plugged in the new sensor and reset it again I believe.
I did it last year so I don't remember perfectly. But I had to some trial and error.

Thanks.
If we don’t short the old cables and just replace them with new ones, will it not allow a reset?

Considering what mechanic has already done I am bit sceptical about his ability to do this trial and error.

Argh, I remember having this when I DIY'd my brakes and changed the pads. There were 2 things that had to be reset, and in a certain order.

I just don't remember the details. I do remember that my inner pads wore out faster than my outboard pads. So I'd check pad thickness once or twice a year and they looked fine. Then the sensor tripped and I didn't really believe it, so I checked and sure enough the inner pads were very worn.

Anyhow, so I ordered all the parts, knew I'd get to it soon, and I recall resetting something... I think I tried to reset the mileage based indicator, hoping that would do it? I don't think it did. I think I tried this through the car, pushing and holding various buttons.

I ended up replacing all the parts, plus the sensor, and thinking that would solve the light, but it didn't.

I think at that point I had Carly out, phone app and dongle, and maybe used it to do a reset, and maybe had do do it again on the car one more time.

I do know for sure there was a point where I was thinking - I replaced the sensor, I even tested that it was working, I reset everything, why do I still have this dumb light?

I think I finally spent some time again trying the resets, maybe I did them both again and it was enough, or I did it in a certain order?

Points being, after that horrible explanation, was 1) I had 2 places to reset, and 2) It was not as straightforward as I expected.

So, you may have a new, or at least functioning, sensor and your mechanic might not be too familiar with BMW resets. I'm sure the actual brakes are fine, FWIW, they're not complicated at all. Just have to figure out the reset details.

tracer bullet wrote

Argh, I remember having this when I DIY'd my brakes and changed the pads. There were 2 things that had to be reset, and in a certain order.

I just don't remember the details. I do remember that my inner pads wore out faster than my outboard pads. So I'd check pad thickness once or twice a year and they looked fine. Then the sensor tripped and I didn't really believe it, so I checked and sure enough the inner pads were very worn.

Anyhow, so I ordered all the parts, knew I'd get to it soon, and I recall resetting something... I think I tried to reset the mileage based indicator, hoping that would do it? I don't think it did. I think I tried this through the car, pushing and holding various buttons.

I ended up replacing all the parts, plus the sensor, and thinking that would solve the light, but it didn't.

I think at that point I had Carly out, phone app and dongle, and maybe used it to do a reset, and maybe had do do it again on the car one more time.

I do know for sure there was a point where I was thinking - I replaced the sensor, I even tested that it was working, I reset everything, why do I still have this dumb light?

I think I finally spent some time again trying the resets, maybe I did them both again and it was enough, or I did it in a certain order?

Points being, after that horrible explanation, was 1) I had 2 places to reset, and 2) It was not as straightforward as I expected.

So, you may have a new, or at least functioning, sensor and your mechanic might not be too familiar with BMW resets. I'm sure the actual brakes are fine, FWIW, they're not complicated at all. Just have to figure out the reset details.

Thanks, i really wanna try it myself as I have ISTA software, but I don't have the jack to lift the car up to remove the wheel.

I actually recall reading something in ISTA+ along the lines of "If the CBS reset is not accepted also after second reset attempt then perform trouble shooting in DSC control unit" So I guess it is possible to do reset but may be matter of do in the correct sequence .

I will test and report back

t4ure4n wrote

I will test and report back

Cool. Sorry for the bad explanation of somethign I don't full remember! I do know that the electronic side of it was in 2 places and I feel like there was a sequence to it perhaps, or for some reason I had to do it several times.

tracer bullet wrote

Cool. Sorry for the bad explanation of somethign I don't full remember! I do know that the electronic side of it was in 2 places and I feel like there was a sequence to it perhaps, or for some reason I had to do it several times.

Was it something to remove fault memory first and then applying the CBS rest?

As far as ISTA is concerned there are errors in two places 1) showing up in DSC module and 2) In CBS reset section where it shows Rear brake pads 0% /2

I've been thinking about it all morning and I just don't remember. Just that I did things in 2 places and it was frustrating. I drove for a few days with the light until I tried enough times in the right way, thinking the whole time "WTF, this should be easy, I did all the steps".

tracer bullet wrote

I've been thinking about it all morning and I just don't remember. Just that I did things in 2 places and it was frustrating. I drove for a few days with the light until I tried enough times in the right way, thinking the whole time "WTF, this should be easy, I did all the steps".

Hi. I managed to get this fixed. I am sharing what I did in case some one else has the same issue.

1. Replace the sensor cable
2. Put the car in neutral
3. Release handbrake
4. Used ISTA to perform CBS reset
5. Clear fault memory
6. Restart the car.