If an error is shown on your electric bike display it is an indication of a possible fault and it needs to be resolved. In this article we will focus on how to fix Bosch 503 error code without a need of visiting Bosch e-bike dealer.
Tools required
- Cross head screwdriver. This is required to adjust the position of the magnet.
- Torx T30. This tool is needed to remove the two screws that hold the mounting plate (motors with the design cover)
- 13 millimetre spanner. This is to remove 2 nuts that hold the mounting plate.
- Torx T20. This tool is required to remove the speed sensor
- Scissors. You may need them to cut the zip tie that holds the cables together.
- Zip tie. May be useful to hold cables together.
How to fix bosch 503 error code by checking the sensor cable
First visually check the sensor and the cable. If it’s damaged then the sensor will have to be replaced.
Removing a speed sensor on Bosch electric bike system.
- To replace the speed sensor first remove the screws on the design cover (older models) or the cable guard (newer models) on the on drive side.
- For the design cover unhook the bottom latch to remove the plastic cover. Remove the cover or the cable guard.
- Remove any zip ties that hold the cables together.
- Now, using your hand or a long nose pliers remove the speed sensor plug from the motor. Notice which slot is used for the speed sensor.
- For the motor with a design cover remove the two screws that hold the mounting plate.
- Now remove the two nuts that hold the mounting plate and remove the mounting plate.
- Gently remove the speed sensor cable.
- Remove the round rubber cap on the sensor.
- Unscrew the sensor and remove it.
Fitting a new sensor
- Screw the sensor onto the frame.
- Fit the round rubber sensor cover.
- Feed the sensor cable over the motor.
- Connect the cable to the motor.
- use cable tie to zip the cables together.
- For the motor with a design cover, refit the mounting plate. Make sure that all the bolts and nuts are tight.
- Place the design cover or the cable guard on the motor.
- Fit the screws and tighten them.
- Refit the crank arm.
How to fix bosch 503 error code by adjusting the position of the magnet
Now check if the magnet on the rear wheel was installed correctly or if it moved. If the magnet is not aligned with the sensor then the sensor will not be able to correctly read the riding data.
- Move the wheel so that the magnet is in line with the sensor.
- If necessary use the screwdriver to loosen the magnet and turn it so that it is facing the sensor.
- There’s a line mark on the sensor.
- Position the centre of the magnet parallel to the line mark and tighten the magnet.
- Restart the system and test ride the bike.
If the problem persists your next step will be visiting your local Bosch dealer.
If there’s an error code showing on your Bosch electric bike display then this means that there is a problem with a speed sensor. Although the Bosch 503 error code on your display might look serious don’t worry as it can usually be fixed easily without the need of visiting a Bosch dealer.
There are two main reasons why the code is showing on your display.
– Damaged speed sensor or the wire. Inspect the speed sensor and the wire and if it’s damaged then replace it or visit your Bosch dealer.
– Incorrect magnet installation. Check if your magnet is aligned with the speed sensor.
– Not an original magnet replacement.
If all those problems are resolved, switch the display off and then on again. The error code should be gone.
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