Bafang error 30: Communication error
Bafang BBS01/BBS02/BBSHD, M-series mid-drives and hub motors (UART & CAN displays)Fix at homeRide with caution
The display and the controller are not talking to each other (UART or CAN bus). The display may power on but show 30, freeze, or show no data; assist is usually blocked. Nine times out of ten this is a connector or cable issue in the main harness.
Likely causes
- Display or controller connector not fully seated or pushed in at an angle
- Water or corrosion in the display or main harness connector
- Damaged wire in the harness, often near the head tube or where it enters the frame
- Wrong display for the controller (UART display on a CAN controller or vice versa)
- Bent pin in the display connector
- Display or controller firmware mismatch after an update
How to fix Bafang error 30
- Switch off, unplug the display connector, check for water and bent pins, clean, dry, re-seat straight and lock the collar
- Do the same at the controller end of the harness if accessible
- Wiggle the harness gently with the bike on: if the code comes and goes, the cable is damaged
- Confirm the display protocol matches the controller (UART vs CAN); Bafang displays are not interchangeable across protocols
- Try a known-good display of the same type if available
- Replace the harness or the display; if both are fine, the controller's communication port is faulty: shop
Go to a dealer if: Go to a shop if a clean connector and a known-good display still show 30, or if the harness runs inside the frame.
Warranty: Bafang parts are usually sold through dealers or online resellers; warranty is typically 1-2 years via the seller, and this code alone is rarely a warranty claim.
Typical cost: Free if it is a connector; a harness is EUR/USD 20-50, a display EUR/USD 60-200, a controller EUR/USD 80-250.
Warranty: Bafang parts are usually sold through dealers or online resellers; warranty is typically 1-2 years via the seller, and this code alone is rarely a warranty claim.
Typical cost: Free if it is a connector; a harness is EUR/USD 20-50, a display EUR/USD 60-200, a controller EUR/USD 80-250.
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.
Frequently asked
How do I reset Bafang error 30?
Power cycle after re-seating the display and harness connectors. The code clears the moment communication works.
Can I keep riding with error 30?
You can pedal home; assist is normally blocked without communication.
Warranty?
A display or controller port failing early is covered; water damage in connectors is often refused.
Related Bafang codes
Not an official Bafang document. Compiled from workshop experience and public service information; details can differ per system version and bike brand.