Bafang motors — whether factory-installed on an e-bike or installed as a DIY kit (BBS02, BBSHD, hub motors) — display their faults as a number: Error 04, 07, 08, 21, 30… The good news: this numbering is stable and well-identified. Here's what each code means and where to start.
How to read a Bafang code
The code appears on the display (DPC, 850C, SW102…). It designates the faulty subsystem: throttle, motor, controller, sensor or communication. The same code can have a nuance depending on the controller firmware, but the family of cause remains the same.
The list of Bafang codes
| Code | Meaning | First check |
|---|---|---|
| Error 04 | Throttle grip does not return to zero | Check the throttle/grip, release it completely |
| Error 07 | Overvoltage | Battery and charger: voltage too high |
| Error 08 | Motor Hall effect sensor fault | Motor connector, Hall cable |
| Error 09 | Motor phase fault | Motor phase connector |
| Error 10 | Controller temperature too high | Let cool down, ventilation |
| Error 11 | Controller temperature sensor | Controller / connectors |
| Error 12 | Current sensor fault | Controller (warranty) |
| Error 13 | Battery temperature fault | Let return to temperature |
| Error 14 | Motor temperature fault | Let cool down |
| Error 21 | Speed sensor | Speed sensor magnet, position |
| Error 25 | Brake signal abnormal (cut) | Brake contactors, connectors |
| Error 30 | Display ↔ controller communication error | Main cable/connector (see below) |
Error 30 — the most common
Error 30 is a communication error between the display and the controller. In the vast majority of cases, it comes from the cable or main connector that links them:
- Turn off the system.
- Disconnect and reconnect the main display/controller connector.
- Inspect the pins (bent, corroded) and moisture in the socket.
- Check that no cable is pinched or cut along the frame.
A cleaned connector and properly seated usually fixes most Error 30s without changing any part.
Error 07, 08, 21, 25 — the other common ones
- Error 07 (overvoltage): often after charging, or an unsuitable battery/charger. Check the voltage and only use the original charger.
- Error 08 (Hall sensor): the controller no longer reads the rotor position. Check the motor connector before suspecting the motor itself.
- Error 21 (speed sensor): like on any e-bike, the sensor magnet has shifted. Realign it.
- Error 25 (brake): brake contactors cut the assistance; a stuck contactor or loose connector triggers the code.
