rkilpa

So I've had my 2009 BMW 550i since February.

The I-drive showed rear brakes were due for replacement in about 1400 miles when I got it with 59000 miles on the ODO. I looked at the pads through the wheel and it looked like they had a lot of meat left so I just assumed the pads were replaced and the system just wasn't reset.

The odometer now reads about 61000 miles (yes, 2000 miles in 5 months) and the I-drive showed that the pads need to be replaced in 600 miles and the system check went from OK and a green checkmark to a yellow triangle with a warning to replace soon.

I looked again and the pads looked thick, so I thought I would just reset the system using the reset procedure that I did when I changed my oil.

The system would not reset and instead the system now shows that I am -15000 miles overdue for a brake service along with a brake warning light on constantly. Great!

Upon searching for the solution to this problem, I read that the brake wear sensor needs to be replaced in order for the system to reset.

My questions are:

If the sensor needs to be replaced to reset the system, is that an indication that the pads are indeed worn to the point they also need replacement? In other words, is the sensor what tripped the I-drive warning from OK to replace soon? I just assumed it was a miles from last reset countdown.

So in summary... I attempted to reset a warning for a service that I could have probably put off for several months. I know I now need to replace at least the brake wear sensor to get my system to reset.

I guess I should replace the pads and rotors anyway since I don't know when they were last changed, but I wasn't planning on this expense so soon.

I have read that Akebono pads and Zimmerman rotors are a good combination. I can get the rear pads, rotors and brake wear sensor for around $280 through partscontainer on eBay. Any other sources offer better pricing?

Also, should I replace the front brakes at the same time, or should I follow the I-drive status? The I-drive shows about 9000 miles until the fronts need to be replaced, too. That's about 2 years of driving for me.

Is it OK to do just one axle at a time? I would never put just new rear tires on when the rears wear out even if the fronts had good tread. I would buy all 4 new tires. Should I do the same with brakes?

Thanks!

twh

(1) It is ok to do one axle at a time.
(2) Follow what iDrive says regarding what axle to do.
(3) The brake pad wear sensor is two stage (shows in iDrive as yellow, then red). Once it gets worn through, you have to replace it or you can't reset the brake indicator on the dash.
(4) According to Bentley, the minimum pad thickness is 3mm for front and rear pads.
(5) According to Bentley, the minimum thickness of rotors for 550i is: front - 28.4mm, rear - 22.4mm. The minimum thickness is also stamped on the rotor. If the rotors are close, I'd change them anyway.

I bought OE pads and Zimmerman rotors from Autohausaz.

If I was you, I'd also change the brake pad spring at the same time.

Be sure and get some disc brake grease for the pad corners.

Clean off the guide pins and replace any (and boots) that are not pristine.

On my wife's 2009 X5, I needed a Torx E18 socket to get the caliper off the car. So, you'll want to have that if you don't already.

westsidebalto

rkilpa, I'm currently having the opposite problem. My CBS says my rear pads have 37,000 miles left, but....it's said that for about three years now (35,000 mi.). I'm not super worried yet, since the pads look good, but still concerned.

twh

I've got a 2006 530xi with 64,000 miles. Original owner. Don't drive too much. Mix of highway and city driving. Front and rear brakes are still the originals. Just listen to iDrive unless you have some other symptom.

srschang

I have a 2008 528Xi with 149,000 miles. I changed the front brakes at 72,000 miles, and the back brakes at 108,000 miles. Both times iDrive told me it was time to change the brakes. I just changed the front brakes again at 147,000 miles, iDrive told me to, and it was right!

rkilpa

As it turns out, I needed brakes. The sensor was indeed sending the correct information to the I-drive. I had maybe 3mm left on the rears and the sensor was worn down too. I was looking at the pad backing which looked like about 5mm thick and all I could see from the angle through the wheels. I'm glad the I-drive wouldn't let me reset the system!

After reading many posts, I decided to go with the R1 drilled/slotted premium rotors and Hawk HPS pads that most members raved about.

Since I decided against the stock look, I ended up doing the fronts at the same time. Now everything not only looks better, but my I-drive is happy once again. I am happy too since I was able to do front and rears for less money than what the rears alone would have cost me had I gone to the dealer for a brake job.

When I reset the system, it shows the fronts are now good for 25,000 miles and the rears for 31,000. Is this what every system resets too?

JasonH

That sounds about right for a reset.

What you'll find is that the miles left will go up before they start going down. I think I've seen mine say over 40,000 miles left.

Atanovich

I recently serviced my brakes at the same mileage and after reset got 31k and 25k as well. FYI the service limit stamped on the rotors is the minimum thickness the rotors can be to be put back into service. I had mine turned by a friend and they were just above the minimum. 3k miles later no problems.

550sport87

Keep in mind the pad sensors are clipped into the inner pads. Most of the time the inner pad wears faster than the outer pad. I've got into a mess at work a couple times because I did an inspection, stuck my tool into the caliper to measure the pad, it measured at 6mm (or whatever) the following week or even days later the customer called back saying their brake light is on and they were told their brakes had some life left. Of course my answer to this is, if you want me to give you an exact measurement of your pads, you'll need to pay me for time to pull all your wheels off, but BMW customers expect everything to be free.
None the less, some sensors Are a 2 stage sensor which monitors the time it takes the burn through the fist part of the sensor, it then calculates a more accurate time frame of how long your brakes will last. Either way.