Error 40 · Err 40 · STUCK_HORN

VanMoof Error 40, explained.

Q: Is Err 40 the same as Error 40?

Yes. The matrix display abbreviates it as Err 40. The bike's internal logs and the Moofment app's diagnostics screen show it as Error 40.

Also shown as Err 40 on the matrix display · symbolic name STUCK_HORN

VanMoof's official documentation says Error 40 "may occur when you press and hold the bell button for a long time, or when you press it too many times in a row." Symbolic name STUCK_HORN — water ingress or a short on the bell line can also trigger it.

What does Error 40 actually mean?

What to try

VanMoof's official troubleshooting sequence is the same for every error code. Work through it in order:

Step 1 — Make sure the latest firmware is installed. Pair your bike with the original VanMoof app (see callout below) and let it apply any pending firmware updates.
Step 2 — Reset your bike. Hold the power button until the bike fully powers down, wait a few seconds, and turn it back on. A 10-second power-button hold is Step 2 of VanMoof's official troubleshooting sequence and often clears transient codes.
Step 3 — Perform a system restart. If the code persists after a reset, do a full system restart from the bike menu.
Still unresolved? Visit a VanMoof Partner for diagnosis and repair. VanMoof's documentation defers to authorised service partners for any error that survives the three universal steps above.

VanMoofer is an independent site. We don't ship parts or repair bikes — we just help you understand what your bike is telling you, using VanMoof's own canonical documentation as the source of truth.

Use the original VanMoof app for firmware updates

Step 1 of VanMoof's own troubleshooting sequence is making sure your bike has the latest firmware — and that update path only exists in the original VanMoof app, not Moofment. Pair the two: VanMoof app for firmware, Moofment for live Bluetooth diagnostics on the S3/X3.

S3 / X3 only

Read Error 40 (and every other code) live.

Moofment connects directly to your VanMoof S3 or X3 over Bluetooth and reads diagnostic codes the moment they appear — with plain-language explanations and no cloud accounts. If you're staring at Err 40 right now, this is the fastest way to confirm what the bike is reporting.

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Frequently asked

What does VanMoof Error 40 mean?

Error 40 has the symbolic name STUCK_HORN. Bell button stuck. It belongs to the button & mechanical group of VanMoof's S3/X3 diagnostic codes.

Is Err 40 the same as Error 40?

Yes. The matrix display abbreviates it as Err 40. The bike's internal logs and the Moofment app's diagnostics screen show it as Error 40 / STUCK_HORN.

What should I try first when Error 40 appears?

Follow VanMoof's official 3-step troubleshooting sequence: install the latest firmware (via the original VanMoof app), reset your bike, then perform a system restart. If Error 40 still appears, visit a VanMoof Partner for diagnosis. See the 'What to try' section above for the full sequence and any code-specific hints VanMoof publishes.

Which VanMoof models show Error 40?

Error 40 belongs to the diagnostic code set used by the VanMoof Series 1 through Series 5 platform. In practice it appears most often on the S3 and X3, because that's where the matrix display surfaces it directly to the rider.

Can I read Error 40 from my phone?

Yes. The Moofment app reads live diagnostic codes over Bluetooth on the S3 and X3. Pair it with the original VanMoof app for firmware updates and you have full coverage.