Brake pad wear - miles remaining on i-drive incorrect

Discussion in '3 Series' started by Adie, Jan 16, 2016.

  1. Adie
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    Adie WARLORD Site Supporter

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    Just a heads-up about a potential problem with the miles remaining on your brakes pads, as displayed via the i-drive.

    Recently I noticed that the miles remaining on my front pads were counting down at an alarming rate, certainly at a faster rate than the number of miles i had driven.

    My car had covered approx 17k miles and it was showing that the front pads were due to be renewed in 1000 miles. I drive enthusiastically on occasions... but not the much! I measured the pad thickness and they had about 9mm on them so probably about 4 - 5mm of useable pad left.

    I booked it into Elms Bedford and they confirmed there is a software issue on some vehicles where it counts down the remaining miles in kilometres... not in miles!! Don't know if this is an accurate diagnosis of the problem but it required a complete reprogramming. The remaining wear of the rear brake pads were also understated.

    The reprogramming was performed under warranty and i now have 10k miles remaining on the fronts and 17k on the rears. I'm now making a note of the actual mileage versus i-drive to make sure it's counting down correctly now.

    So... the moral of the story is to check your car isn't affected whilst it's still under warranty!
     
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  2. Kev2005
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    Kev2005 WARLORD Site Supporter Good Egg

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    hi, interesting....

    My car (320d ED 2012) has been saying around 20k rear and 60k front since i got it, upon checking the other day it is showing 21k rear, 60k front.... now i don't tend to slam the brakes on or leave my breaking right to the last minute but on occasion where required i do need to brake hard but somehow the i drive still shows 21k rear, 60k front.... car is now coming up to 4 years old, i had it when it was a little over 1 year old with just over 2.5k miles on it, never changed the pads or tyres yet and car has done around 21.5 - 22k miles so far, is out of warranty but I am paying extended warranty, maybe i should ask them to check the pads when I take it in for a service/MOT in April? or do they check them anyway to be sure?
     
  3. Adie
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    Adie WARLORD Site Supporter

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    Sounds as if you've got the opposite of the situation i had!
    20k rear and 60k front doesn't seem right on the original pads with 22k miles already on them... the fronts will always wear out quicker than the rears... at this rate the i-drive reckons your fronts will cover 82k miles before needing to be changed!!

    They'll check your pads during a service, get them to tell you how many mm you've got left on them, i think new pads come with about 12mm
     
  4. Kev2005
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    Kev2005 WARLORD Site Supporter Good Egg

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    hmm I will double check i got them right way round next time i use the car..
    im sure that's what it said but will double check...

    Yeah i'll ask them to tell me the mm left on the pads. I was just expecting it to go down a bit but its remained at the same amount, if anything gone up slight... since i had it... for ages it say 20k/60k, now it shows 21k/60k.. i'll double check which is which reading.

    Thanks!
     
  5. kleynie
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    kleynie WARLORD Site Supporter

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    I'm on 43k now and still showing 15k on the front pads, which seems too much to me. But there does still seem to be meat on them.
     
  6. Adie
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    Adie WARLORD Site Supporter

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    Seems weird how they can differ so much. Your 530d is a lot heavier then my 335i yet it looks as if you'll get close to 60k out of your fronts whereas i'll only be getting 27k out of mine at best :( Perhaps influenced by the type of driving?... motorway / non-motorway
     
  7. Peter
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    Peter WARLORD

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    Very common these days for rear pads to wear out as fast, or faster, than the front brakes. Rear brakes do a lot more work than we may think, DSC and traction control.

    My car the rears do more work, appears a rear bias for light braking, same in my E91 330d. My E39 was the opposite, rears did little work, even with a V8 up front.

    As to the CBS getting in a knot, that is possible, had to have my rear brakes reset as wear was showing faster than the actual pad wear. Garage reset/added about 30k miles to reflect distance driven vs. pad wear rate.

    There is a factor which can come into play with the CBS for brake wear, involves the 1st stage of the sensor, which sets the wear rate from new/new pads. Drive differently after that initial calibration and logically pad wear will not match the CBS countdown. That is likely what happened with my car. When I took over, my driving pattern is likely to be much different than the original BMW user.

    BTW, I'm at 30k miles with over 40k miles more use anticipated for the front pads, 30k miles for the rear. Looking at pad wear rates, that is probably about right for the rear, but over cautious for the front.

    Peter
     
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  8. Copex
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    Copex

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    My last car 320d had this issue. My dealer sorted it out and reprogram was done.
     
  9. Mieke
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    Mieke WARLORD Site Supporter

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    Why do manufacturers over-complicate things. Who really needs to know that you have 40k miles remaining on the brake pads? The wear indicator embedded in pads with 4 mm left has always worked OK without problems.

    BTW I changed the original brake pads on my Golf Gti at 95k (still not down to the wear indicators) when I had the brakes serviced. I don't tend to use the brakes a lot - it slows the car down too much! :D
     
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  10. Chris.T
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    Chris.T

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    Mine seem to wearing slower than the i drive suggest and dealer keeps resetting, the whole thing just seems overly complex to me as said above what is wrong with pads with indicators embedded in them and a light on the dash, modern technology at its best eh:rolleyes:
     
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  11. Adie
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    Adie WARLORD Site Supporter

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    Just had my key read at the dealership. Now got 8,699 miles until front brakes need replacing, last reading showed 9,321 miles (diff = 622 miles)... but car has only covered 163 miles!!
    Meanwhile the rears are identical, 16,777 miles both times... so the reprogram hasn't made a difference. Will ignore and wait until the yellow light comes on... like in the good ol' days !
     
  12. K777
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    K777 WARLORD

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    Had same on my 640d. New pads a few thousand miles later shot down to 9000 left then went down a 1000 every 200 miles until it hit 2000


    Blamed sensor coming off. After blaming my braking ( yeah right - I can't say what I replied to that)

    Happened again after 1000 miles

    Then they replaced sensor. After first being met with a barrage of abuse when they told me car needed flashing over night. And that wasn't covered in bmw extended warranty. They didn't flash it. They agreed to try a new sensor.

    Sensor was free.

    Part ex'd car after 1000 miles so don't know if sensor cured it.

    There was no way I was paying when I was moments away from a part exchange.
     
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  13. Adie
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    Adie WARLORD Site Supporter

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    Thanks K777 ,hopefully that could be the answer. They've flashed mine under warranty but this hasn't rectified the problem... i'll certainly get them to replace the sensor before it's outside warranty. Thanks agian
     
  14. rigeng
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    rigeng

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    After reading this thread I took the wheels off my car yesterday to check remaining pad thickness. Front was 7.5mm, and i-drive said replace in 29000 miles. Rears were down to 3.5mm with i-drive saying replace in 2900 miles. So probably the i-drive is not too far out.

    And thanks to Adie for a timely reminder(y)
     
  15. Adie
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    Adie WARLORD Site Supporter

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    Your's seems to be working as designed... unlike mine :( Hopefully a new sensor will solve my issue, thanks to the heads-up from K777
     
  16. Kev2005
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    Kev2005 WARLORD Site Supporter Good Egg

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    hi all,

    Just checked car...

    front brake pads: 60k left
    rear front pads: 21k left

    service due this year is: engine oil (april), vehicle check(april) (not entirely sure what this is ?) and vehicle inspection (think this is MOT?) due May.

    Planing to take car in towards end of April and have them do all 3 in 1 visit to avoid multiple trips.

    Kevin
     
  17. Adie
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    Adie WARLORD Site Supporter

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    60k left !!... my car has only covered 17k miles and says i need new front pads in 9,000 miles... but at the rate it's clocking down this will be in 2,500 actual miles!
     
    Last edited: Jan 20, 2016
  18. Peter
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    Peter WARLORD

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    Not sure how a new sensor on worn pads can sort the CBS mismatch.

    My understanding is the sensor wears with the pad from new. On a worn pad, how can a new sensor 'set' the parameters for CBS countdown?

    From BMW's description:

    As I read it, the critical part has to be the new, < 5 Ohms reading, to the mileage when it triggers the 470 Ohms resistance. Setting the CBS countdown rate.

    Peter
     
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  19. Adie
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    Adie WARLORD Site Supporter

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    Excellent! thanks Peter... i've been googling to try to understand how it works. Where did you get this info from?
     
  20. Adie
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    Adie WARLORD Site Supporter

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    A quick question Peter....
    Just to confirm i've got this right... if i have new pads / sensor fitted and the CBS is reset it will again measure the wear rate to determine the remaining miles on the new set of pads, have i understood this correctly? Thanks
     

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