Error 21 indicates there is an issue with the amount of voltage or current being supplied to the internal controller and motor.
This can often be resolved by resetting the display. Carefully removing the battery, inspecting the terminals and re-installing the battery gently.
If the issue persists, the cause may be:
- Internal controller (50%)
- Motor (30%)
- Battery (10%)
- Wire from motor to controller (10%) - if it shows signs of damage at connections
Resetting your display to default
This is done from the main screen by holding the middle (Power) and top (+) button on your display at the same time. Select reset to default 'yes' and hold the middle button to enter that setting. These steps can be reviewed in our display tutorials:
Access to another bike
If you have access to another bike (with matching specs or components), you can test the motor easily or swap the internal controller, which could expedite the resolution. Check the following article for more info: Advanced troubleshooting steps
Checking wires and connections
Please take pictures where requested to share with our support team if necessary.
This will likely resolve this issue faster.
- 500 Series Motor Not Working
- 700 Series Motor Not Working
- LMT'D Motor Not Working
- Core-5 Motor Not Working
If you have checked your connections and reset your display without resolving the issue, please contact our support team for further assistance.