Home › Diagnosis › Bafang reset: display defaults, service menu password, parameter reset via programming cable (with warning) and error memory
Bafang reset: display defaults, service menu and the programming cable you should think twice about
ResetsBafang (DP C18, 850C, C961; BBS motors)
Bafang systems (BBS01/02/HD mid-drives, M-series, hub motors) come with displays such as the DP C18, 850C, C961, 500C and DP C11. The display holds units, wheel size, speed limit and assist level count; the controller holds the real parameters. A display reset is harmless; a controller parameter reset via USB cable is where people brick bikes.
Warning: Do not write controller parameters with a programming cable unless you have first READ and SAVED the current parameters to a file. Wrong values (battery cut-off, current limits, PAS settings) can shut the bike down permanently, overheat the motor or make it illegal on the road. A display 'defaults' reset can also zero the display odometer, which matters if you sell. A Bafang error (e.g. 04, 07, 08, 21, 30) is not cleared by any reset: it returns until the cause is fixed.
What you need
- Battery above 20%
- Wheel size, speed limit and current settings written down (photo of every settings page)
- For the parameter route: the correct Bafang USB programming cable, a Windows PC with the Bafang configuration tool, and a saved backup file
Step by step
1. Soft reset: display off and on
Press and hold the power button on the display or control pad until it turns off. Wait 5 seconds. Hold to switch on.
If OK: Error code gone and stays gone.
If not: Code returns: power cycle.
Press and hold the power button on the display or control pad until it turns off. Wait 5 seconds. Hold to switch on.
If OK: Error code gone and stays gone.
If not: Code returns: power cycle.
2. Full power cycle: battery out
Switch off, unlock and remove the battery. Wait 30 seconds. Check the discharge connector for burnt or loose pins while it is out. Refit, switch on.
If OK: Boots clean.
If not: Same error: see the Bafang error code page for the number. Typical: 04 throttle, 07 overvoltage, 08 hall sensor, 21 speed sensor, 30 communication.
Switch off, unlock and remove the battery. Wait 30 seconds. Check the discharge connector for burnt or loose pins while it is out. Refit, switch on.
If OK: Boots clean.
If not: Same error: see the Bafang error code page for the number. Typical: 04 throttle, 07 overvoltage, 08 hall sensor, 21 speed sensor, 30 communication.
3. Display defaults: DP C18 / DP C11
Bike on. Hold + and − together for about 2 seconds to open the settings. Scroll to 'Set defaults' / 'Restore' (wording varies), select and confirm. Then re-enter wheel size (Wheel), speed limit and units.
If OK: Display back to stock; wrong speed or units fixed. Check the wheel size, a wrong value is the most common 'my speed is wrong' cause.
If not: Display frozen or shows the Bafang logo only: the 5-pin display cable or the display itself. Swap-test with a known-good display if you can.
Bike on. Hold + and − together for about 2 seconds to open the settings. Scroll to 'Set defaults' / 'Restore' (wording varies), select and confirm. Then re-enter wheel size (Wheel), speed limit and units.
If OK: Display back to stock; wrong speed or units fixed. Check the wheel size, a wrong value is the most common 'my speed is wrong' cause.
If not: Display frozen or shows the Bafang logo only: the 5-pin display cable or the display itself. Swap-test with a known-good display if you can.
4. Display defaults: 850C / 500C / C961
850C/500C: hold the 'i' button about 2 seconds to enter settings; find 'Reset' / 'Factory defaults'. C961: hold the two arrow buttons; settings include wheel diameter, speed limit, backlight and a reset item on later firmware. Confirm and re-enter wheel size and speed limit.
If OK: Stock display settings.
If not: No reset item on your firmware: nothing more to reset in the display.
850C/500C: hold the 'i' button about 2 seconds to enter settings; find 'Reset' / 'Factory defaults'. C961: hold the two arrow buttons; settings include wheel diameter, speed limit, backlight and a reset item on later firmware. Confirm and re-enter wheel size and speed limit.
If OK: Stock display settings.
If not: No reset item on your firmware: nothing more to reset in the display.
5. Service menu password note
Some Bafang displays hide a second menu behind a password (widely published values are 1919 and 0512 on older DP/C-series units; some brands use their own). It gives access to speed limit, current and PAS options. Change only what you understand and photograph the page before you change it. Raising the speed limit above the legal limit makes the bike a moped in most jurisdictions.
If OK: You changed one value, tested, and it did what you wanted.
If not: Wrong entries made the bike weak or dead: enter the menu again and restore the photographed values, or use the display defaults item.
Some Bafang displays hide a second menu behind a password (widely published values are 1919 and 0512 on older DP/C-series units; some brands use their own). It gives access to speed limit, current and PAS options. Change only what you understand and photograph the page before you change it. Raising the speed limit above the legal limit makes the bike a moped in most jurisdictions.
If OK: You changed one value, tested, and it did what you wanted.
If not: Wrong entries made the bike weak or dead: enter the menu again and restore the photographed values, or use the display defaults item.
6. Parameter reset via programming cable (strong warning)
Only if the controller behaves wrongly (no assist above level 1, cuts out at a certain current, wrong PAS start) and you know it was programmed before. Connect the Bafang USB cable between the display connector and the PC, open the Bafang configuration tool, click 'Read' on every tab and 'Save' the result to a file. Only then load a known-good parameter file for YOUR motor and battery voltage and 'Write'. Never write with the battery below 50% or on a laptop that may sleep.
If OK: Controller responds normally; assist levels and PAS are sane.
If not: Write fails or the bike is dead afterwards: reload your saved backup. If the controller no longer answers, it needs a dealer or a replacement controller. Nothing else you can do at home.
Only if the controller behaves wrongly (no assist above level 1, cuts out at a certain current, wrong PAS start) and you know it was programmed before. Connect the Bafang USB cable between the display connector and the PC, open the Bafang configuration tool, click 'Read' on every tab and 'Save' the result to a file. Only then load a known-good parameter file for YOUR motor and battery voltage and 'Write'. Never write with the battery below 50% or on a laptop that may sleep.
If OK: Controller responds normally; assist levels and PAS are sane.
If not: Write fails or the bike is dead afterwards: reload your saved backup. If the controller no longer answers, it needs a dealer or a replacement controller. Nothing else you can do at home.
7. Error memory
Bafang displays show the current error only; there is no user-readable error history. The dealer's BESST tool reads the controller and battery logs, updates firmware and can pair a replacement controller or battery. Not all shops have BESST; ask before you go.
If OK: Log read, cause found.
If not: No BESST dealer near you: the error code itself plus a multimeter and a look at the hall sensor / speed sensor wiring is the usual home diagnosis path.
Bafang displays show the current error only; there is no user-readable error history. The dealer's BESST tool reads the controller and battery logs, updates firmware and can pair a replacement controller or battery. Not all shops have BESST; ask before you go.
If OK: Log read, cause found.
If not: No BESST dealer near you: the error code itself plus a multimeter and a look at the hall sensor / speed sensor wiring is the usual home diagnosis path.
What you now know for sure
- Transient: Gone after off/on or power cycle. → Nothing to do.
- Display settings: Wrong speed, units or assist count fixed by display defaults and re-entered wheel size. → Done. Photograph the settings for next time.
- Controller parameters: Bike was programmed previously; parameter reset with a backup fixed it. → Keep the backup file. Do not change values you cannot explain.
- Hardware fault: Error code survives every reset. → Bafang error page for the code, then a dealer with BESST or a replacement part.
- Bricked by programming: Controller no longer responds after a write. → Try the backup file once; otherwise replacement controller.
Manuals and video
Frequently asked
Does a Bafang display reset erase the odometer?
On many Bafang displays the ODO is stored in the display and a defaults reset sets it to zero. That is why a Bafang bike with '312 km' and a worn chain deserves suspicion.
Is the Bafang service password 1919 or 0512?
Both are widely published for older DP-series and C-series displays; some brands change it. If neither works, your display uses a brand-specific code and a dealer has it.
Can the Bafang programming cable fix an error code?
No. It changes controller parameters, not faults. An 08 (hall sensor) or 21 (speed sensor) stays until the sensor or wiring is fixed.
Still stuck? Take a photo of the display and show it to a local e-bike workshop. Bring the bike's system name (e.g. Bosch Performance Line CX) and the exact code; that saves diagnostic time and money.