RideFixer

Generic displays error code

Generic displays error 21: Speed sensor fault

Medium severity Service soon

Can I ride home with this error?

Ride with caution. Safe to pedal without assist.

What it means

The system cannot read wheel speed. C961 uses Bafang protocol V4.0.

Likely causes

  • Speed sensor or magnet moved
  • Damaged cable

Symptoms

  • 21 flashes
  • Motor stops

How to fix it

  1. Check the speed sensor and magnet line up.
  2. Check the sensor cable.
  3. If the code stays, take the bike to your dealer or an e-bike repair shop.
Still showing 21? The RideFixer app finds bike shops near you, so you know where to take it.

How urgent is it?

Needs checking.

Applies to

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