Bafang error 37: Watchdog (WDT) error
Bafang CAN systems (M400/M500/M600/M620, DP C18 CAN, 850C/860C CAN)Dealer neededRide with caution
The controller's watchdog timer detected that its firmware stopped responding and forced a reset. A one-off can be a glitch; repeated 37 codes mean unstable firmware or failing hardware.
Likely causes
- Firmware crash, often after a failed or interrupted update
- Unstable power supply to the controller (bad battery contacts)
- Controller hardware degradation
- Electrical noise from a faulty peripheral
How to fix Bafang error 37
- Power cycle and ride a short test
- Clean the battery contacts and check the battery is seated firmly
- Have the controller firmware updated with the Bafang tool (dealer)
- Replace the controller if the code repeats after a firmware update
Go to a dealer if: Go to a shop if the code repeats; a dealer can reflash the controller before replacing it.
Warranty: If the bike or kit is under warranty (usually 1-2 years via the seller), contact them before opening anything, as opened motors and controllers can void the claim.
Typical cost: Firmware update EUR/USD 20-60 at a dealer; controller EUR/USD 100-300.
Warranty: If the bike or kit is under warranty (usually 1-2 years via the seller), contact them before opening anything, as opened motors and controllers can void the claim.
Typical cost: Firmware update EUR/USD 20-60 at a dealer; controller EUR/USD 100-300.
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
Can I reset error 37?
Yes, a power cycle resets the watchdog. Repeats mean a real problem.
Can I keep riding?
After a single event yes, cautiously. If it repeats, assist can drop out unexpectedly.
Warranty?
Yes, firmware and controller faults are covered.
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.