Bafang error codes: what do they mean and how can they be resolved?
Bafang error codes are your e-bike's internal communication system: they indicate precisely which malfunction is preventing the motor, battery, or sensors from working properly. Whether it's a simple loose connection or a faulty Hall sensor, each code helps you diagnose the problem without replacing parts at random.
Before analyzing the codes one by one, there is always one essential step: check all physical connections. Vibrations, rain, dirt, or wear and tear can disrupt connectors and prevent data or power from flowing properly. A quick visual inspection of plugs, cables, and pins often solves the problem.
In this article, you will find an overview of the most common Bafang error codes, such as codes 04, 05, 21, and 30, along with their probable causes and solutions. This information applies to popular motors such as the BBS01, BBS02, and BBSHD.
Written by: Hanna Stevens | December 4, 2025 | Reading time: 6 minutes
More about the author: Hanna Stevens
Hanna is an avid cyclist who loves exploring new routes and sharing her experiences to inspire others to get on their bikes more often.
Key findings
- Bafang error codes directly indicate which component is behaving abnormally: acceleration trigger, speed sensor, or controller.
- Loose or damaged cables are the number one cause of problems, which is why it is important to check all connections first.
- Many errors can be resolved by yourself, but persistent problems related to sensors or the controller may require replacement of a component.
1. Errors related to the throttle trigger
These errors indicate a problem in the acceleration system, which allows direct control of speed.
| Error code | Description of the problem | Solution |
|---|---|---|
| 04 | The trigger does not return to the neutral (non-reactive) position. | Check whether the trigger can physically return to the "off" position. Inspect the cable for kinks or damage. Disconnect the trigger: if the error disappears, replace it. |
| 05 | Accelerator trigger malfunction. | Check the connector and cable for the trigger. Disconnect it. If the problem persists, contact your dealer. |
2. Voltage protection
These errors concern the battery voltage safety thresholds.
| Error code | Description of the problem | Solution |
|---|---|---|
| 06 | Low voltage protection: the battery is not providing enough voltage. | Check the battery voltage. Fully recharge it. Also check the battery connections. |
| 07 | Overvoltage protection: the battery is supplying too high a voltage. | Remove and reinstall the battery. Check that you are using the correct voltage (48V or 52V for BBS02/BBSHD). If the problem persists, contact your dealer. |
3. Engine and sensor errors
These codes indicate problems related to internal engine components or sensors essential to operation.
| Error code | Description of the problem | Solution |
|---|---|---|
| 08 | Abnormal signal from the Hall sensor in the engine. | Check the motor connector and the extension cable. Make sure the pins are not bent. If the problem persists, it may be necessary to replace the Hall sensor, the controller, or the motor. |
| 09 | Motor phase wire failure. | Check the motor and motor cable connectors. Replace the extension cable, screen, motor, or controller as necessary to isolate the fault. |
| 21 | Speed sensor error. | Restart the system. Check the magnet on a spoke: it must be aligned with the sensor and located 0.4–0.8 in. (or 1–2 mm depending on model, smooth side facing the sensor). Check the sensor connector. Update the controller. If the error persists, replace the RPM sensor. |
4. Temperature and communication errors
These errors relate to the overheating of certain components or data exchange problems.
| Error code | Description of the problem | Solution |
|---|---|---|
| 10 | Maximum internal temperature reached (safety). | Turn off the bike and let it cool down (several hours). Avoid heavy loads in hot weather. If this happens for no apparent reason, the motor or controller may be defective. |
| 13 | Internal battery temperature sensor error. | If the message appears after exposure to sunlight or while riding, allow the battery to cool down. If the error persists, replace the battery or controller. |
| 30 | Communication problem: the screen is not receiving anything from the controller. | Check all connections. The screen is often the problem. Check cables and pinches. Try with another screen or controller. A software update may help. |
5. Other important codes
Other critical errors that sometimes require professional intervention:
- 12: Current sensor error in the controller: usually indicates a faulty controller after a software update.
- 25/26: Torque sensor error: check the connectors. Perform a calibration reset by turning on the system without applying any pressure to the pedals.
- 33: Brake signal error: if you have brake sensors, check all connectors and ensure that the levers are not stuck. Also check the position of the sensor magnet.
If you have checked the connections, restarted the system, and allowed the components to cool down, but the problem persists, contact your dealer.
FAQ
What is the most common cause of Bafang error codes?
Loose, dirty, or damaged connectors. It is therefore always recommended to check the connections before replacing a part.
Can I continue driving with an error code?
Sometimes yes (e.g., a slight speed sensor error), but for engine, voltage, or temperature errors, the system often shuts down automatically. Continuing to drive can cause damage.
Can a software update resolve errors?
Yes. Communication or sensor signal issues can be fixed by updating the firmware or controller, if available.
How can you tell if a sensor or controller is actually defective?
If, after checking the cables, cleaning the connectors, restarting the computer, and testing with another monitor or extension cable, the problem persists, the component is probably defective.
Is it safe to replace a Hall sensor or controller yourself?
Yes, if you are technically skilled and equipped with the right tools. If in doubt or for complex errors (08, 09, 12, or 30), it is advisable to consult a specialist.