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Bafang display error codes

Bafang error 21
Speed sensor error

The system isn't getting a proper wheel-speed signal, so it may limit or stop assistance.

Checked against Bafang's own manual: October 23, 2026.

Check your display first. These are the codes Bafang's own displays use. Many bikes with Bafang or Bafang-style motors have a display made by another company, and its numbers can mean something different. If your display isn't a Bafang one, use that display's manual, or send us a photo.

What Bafang says

Speed sensor fault.

Bafang's recommended steps

  1. Switch the system off and on.
  2. Check the magnet on the rear wheel spoke is still there and passes 10–20 mm from the sensor. Don't bend anything.
  3. Check the speed sensor's plug is connected (look; don't pull hard).
  4. If the problem continues, contact your retailer or a shop that works on Bafang systems.

Summarized from Bafang error code sheet (error 21), checked October 23, 2026. Follow the link for Bafang's exact wording.

If it keeps coming back

If the code comes back after a restart, have it checked by a mechanic who works on Bafang systems. Bikes Plus works on Bafang and Bafang-style systems all the time.

Write down the code and what you were doing when it appeared. That saves time at the shop.

Call Bikes Plus Email a photo

Make sure it's a Bafang code

Error numbers mean different things on different systems. This page covers bikes with a Bafang display (the Bafang name or logo is usually on the display or its back), on Bafang mid-drive and hub-motor systems. Displays with a screen keep the last 10 codes in the INFO or ERROR menu. LED-only displays flash the code: the first light flashes the tens digit and the second the units, so two flashes then five is 25.

All Bafang codes Step-by-step checks