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VanMoof error 51: Motor fault (voltage fault)

VanMoof S3 / X3 (also S5 / A5 where applicable)Dealer neededDo not keep riding

Errors 49 to 53 are a group of motor controller faults on VanMoof: controller error, over-current, under- or over-voltage on the motor side, and internal controller checks. Error 51 points at a motor-side voltage outside the expected window, often battery sag. In practice they share the same causes and the same repair path, and assist is cut until it is fixed.

Likely causes

Motor controller board fault in the front hub
Damaged or shorted motor cable, especially where it runs through the fork and steerer
Voltage sag from a tired battery under load, read by the controller as a motor-side fault
Water ingress in the motor or connector
Firmware mismatch between cartridge and motor after a partial update

How to fix VanMoof error 51

Charge the battery fully and do a hard reset (10 to 15 seconds on the power button)
Check whether the fault appears only under load or with a low battery; if so, the battery may be the real cause
Steer fully left and right with the bike on to see whether the code reacts to cable movement
Install any pending firmware update with the charger connected
If the code remains, an independent VanMoof-capable shop can log the controller data and test the motor, cable and battery separately

Go to a dealer if: Go to a shop if the code stays after a full charge and reset, or if it comes back on every ride.
Warranty: Warranty from the original VanMoof B.V. died with the 2023 bankruptcy; the relaunched VanMoof (LAVOIE/McLaren Applied) only covers bikes sold by them after the relaunch, so most S3/X3 owners pay for repairs.
Typical cost: Diagnosis around EUR 50-100; controller or motor replacement EUR 300-600, motor cable repair EUR 100-250.

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

Is error 51 the motor or the battery?

It can be either. A weak battery sagging under load is often reported as a motor-side voltage fault. A shop can tell in minutes with a load test.

Can I ride with error 51?

No assist, so only to get home. If the fault is a short, do not keep power cycling.

Are errors 49 to 53 all the same?

They are one family of controller faults with slightly different triggers. VanMoof did not publish the exact differences, so treat them the same: charge, reset, then shop.

Related VanMoof codes

49 · Motor fault (controller error)50 · Motor fault (over-current)20 · Sudden battery shutdown

Not an official VanMoof document. Compiled from workshop experience and public service information; details can differ per system version and bike brand.