Speed Sensor Adjustment for Bosch error 503

If your Bosch display shows error 503, this is likely caused by misalignment between the magnet on your spoke and the speed sensor on your bike frame. You should be able to resolve this by adjusting the placement of your spoke magnet. 

  1. Check to make sure there is a magnet (18) attached to a spoke of the rear wheel.
  2. The spoke magnet should be 5 to 17mm away from the speed sensor (18).
  3. The magnet should also pass over the marked line on the sensor.

Here is a YouTube video that shows the adjustment, too: https://youtu.be/P6MZatLa8JQ?t=80

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