BMW E46 Yaw Sensor Replacement

What is a BMW post doing on a Mustang racing site? It’s one of our daily drivers, and one of our favorite road trip/parts runner/carry-all cars. Our particular example is a 2001 E46 wagon in classic Alpine white, featuring a manual transmission, coil-overs, OEM Euro clear corners and taillights, DIY Plasti-Dip shadow-line trim, tinted windows, and Alpina 18×8 wheels.

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The particular problem we’ll address today with our little BMW is a yaw sensor failure, with revealed itself by the ABS/TCS system grabbing the passenger front caliper for a millisecond, then illuminating the ABS and TCS lights, indicating an error in the system. This happened within minutes of driving the car, and was quite noticeable and alarming. Scanning the code with our OBDII reader showed a yaw rate error, leading us directly to the yaw sensor itself. We researched online, and came across tested yaw sensors on eBay, part number 1166003. $59.99 later, we had a verified good sensor sitting on the workbench.

First, we gathered the necessary tools for the job:

  • 3/8″ Ratchet
  • 3/8″ 16mm Socket, Deep
  • 1/4″ Ratchet
  • 1/4″ 10mm Socket
  • 1/4″ 1-1/2″ Extension
  • 1/4″ 1-1/2″ Extension, Wobble
  • 1/4″ Universal Joint
  • 1/4″ Driver
  • 10mm Box-End Wrench, Ratcheting
  • 5mm Hex/Allen Wrench
  • Wire Cutters
  • Magnetic Helper
  • Pry Bar
  • Flashlight
  • Matador Surface

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The sensor is located in the floor, just in front of the driver’s seat. We unbolting the driver seat, with two 16mm nuts under plastic covers up front, and two 16mm bolts out back.

We tilted the seat back, without disconnecting it’s wiring harness. Underneath the seat, a wiring harness is zip-tied to a plastic bolt. We cut it with the wire cutters, then turned the bolt by hand to remove.

Next, we used the pry bar to pop the lower inner door trim plate. This plate is held on by 4 plastic clips and was very stubborn.

We then pried the front section of the carpet back, exposing the bracket holding the yaw sensor.

The bracket is covered by a wiring harness, which we moved to the side, using the seat stud to hold the harness out of our way. The bracket is held on by four 10mm bolts, two of which are visible at the top of the bracket, already removed in the above picture

The lower bolts are quite difficult. The first bolt, on the outer side, can be accessed by removing the ground point with the 10mm box wrench, then removing the 10mm bolt on the bracket with the 1/4″ drive and both extensions, using the wobble extension to get the 10mm socket on the bolt. The last bolt is impossible, in our opinion, without doing a little demolition work. We used the pry bar to cut through the Styrofoam, to allow for us to use our extensions and the universal joint to get the socket on the bolt.

 

The bracket itself was then able to be removed, and the sensor unplugged via a simple push clip. We used the 5mm hex/Allen wrench to remove the two bolts holding the sensor to the bracket. Installation, as they say, is the reverse of removal. We bolted the sensor to the bracket, and the bracket to the body. We reconnected the ground point, and placed the chunks of Styrofoam back in place. Then fold the carpet back down, screwing in the plastic bolt, using a new zip tie to hold the wiring harness in place. Replace the lower inner door trim, then re-position the seat and bolt it back into place.

A quick test drive showed no more errors, and after a few trips with the car, we’ve declared the problem completely resolved!

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