How to Replace your BMW E90/E91/E92 Brake Pad Sensor
Your BMW brake pad sensor is what controls the “brake” light on your dashboard or iDrive system and lets you know how much life you have left in your brake pads. The sensor mounts onto the brake pad; once the brake pads fully wear down, the tip of the sensor is breaks which trips the wire and results in the dashboard light. If you use an OBD scanner, the brake pad sensor fault codes are:
- 5F12, 5F13, 5F14, 5F15, and 5F16
The brake pad sensor should be replaced every time you replace your brake pads! You don’t have to replace the sensor every time, but not doing so can result in you getting an inaccurate reading on the amount of life left on your pads, and result in the notification always appearing on your dash/iDrive system. Once the light comes on the dash, the only way to remove it is to either replace the sensor or bypass the sensor which will cause it to no longer read the pad life anymore.
Brake Pad Sensor Location:
E90’s have two sensors, one for the front side and one for the rear side.
- Front, driver side wheel well
- Rear, passenger side wheel well
Tools Needed for Brake Pad Sensor DIY:
Brake Pad Sensor Parts:
- OEM Bowa Brake Pad Sensor – Part # 34 35 6 789 440
This part fits both the front and the rear.
E90 Brake Pad Sensor DIY Steps:
Step 1. Jack the car up, remove the wheel, and remove the wheel well liner. Removing the liner requires a bunch of 10mm plastic nuts and 8mm screws. Here is a before and after pic with the liner removed:
After the liner has been removed:
Step 2. The brake pad sensor is located within a little black box in the upper left hand side of the wheel well. You can see it in the above picture – its where the white and black cylinder shaped wires are. There is a cover that goes over these two sensors, but it has been removed in the above picture. Here is a comparison of the new sensor to the old sensor:
Step 3. Unsnap the old sensor from its holding place, it should easily pull out. Disconnect the wire and reconnect it to the new brake pad sensor. We’re starting from the connection with this DIY – you can start the opposite way by removing the actual sensor from the brake pad first if you’d like. The new sensor should snap right back into place and now we can change that actual sensor piece that hooks onto the brake pad.
You’ll notice the old wire is still connected to a few things to hold it into place. Just make sure you secure the new sensor wire properly by snapping into the same spots as the old sensor.
Step 4. Locate the connection where the sensor attached on the brake pad. You’ll see the sensor right on the face of the brake caliper. Use a flat-head screwdriver to pop the old sensor out of place, and reconnect the new sensor. You might have to play around with it a bit to get it to properly reconnect. Once you’ve got it reconnected, make sure the remainder of the wire is correctly set and not dangling.
Step 5. Replace the wheel well liner, the 10mm and 8mm bolts for the liner, the wheel, and then put the car back on the ground. The new sensor is in and good to go! But…the light will still be on your dash.
Step 6. Now we need to reset the brake pad service light. To do so, you have two options. Occasionally the instrument cluster method doesn’t work and you’ll need to reset it with an OBD scanner.
- Reset the sensor via the instrument cluster:
- start by turning the ignition on but not starting the engine.
- Find the reset button on the bottom left of the gauge cluster. Press and hold it for a few seconds until you see the service menu appear in the mini LCD screen in between the speed gauge and RPM gauge.
- Keep pressing the reset button until you see the brake light symbol show up on the screen.
- Press and hold the reset button again until you see the words “RESET” appear on the screen.
- Once this text is displayed, release the button and then press it again for approx. 5 seconds the reset the light.
- Reset the brake pad sensor with an OBD scanner:
- You need to get a proper OBD-II scanner that can access and reset this information on the car. We recommend this scanner. Note: there are cheaper Foxwell scanners out there, but the cheaper ones do not have the ability to reset brake pad sensors for BMW’s.
- The process will differ depending on which scanner you are using, but generally, you should access the control unit, then the chassis, then you should see an option for ABS/ASC/DSC.
- Read the fault codes for the ABS/ASC/DSC unit.
- You should see a code for the bad break pad sensor.
- Under the service > maintenance setting, you should be able to reset the front and rear break settings separately.