Error 10 on the SW900 means “Communication receiving problem.” Most likely cause: a loose, wet or damaged display cable, or a display that doesn't match the controller. Try this first: turn it off and on again.
The display and controller talk through a thin data cable. This code means the display isn't receiving data from the controller. Usually the display plug is loose, wet or corroded, or the cable is pinched. The display and controller must also be a compatible pair that uses the same communication protocol, so this is common right after fitting a new display.
Step-by-step checklist
Work from the top. Steps go from free and easy to shop jobs. Switch the bike off before touching any connector. Tick each step as you go. Your progress is saved on this device.
Parts you might need
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Only buy a part if the free steps didn't fix it. Always match the voltage and connector type to your bike.
Electrical contact cleaner spray
Cleans dirt and corrosion from connector pins and battery contacts.
Link coming soon
Dielectric grease
A thin coat on connector seals helps keep water out after you clean them.
Link coming soon
Display extension cable
Replaces a pinched or damaged display cable. Must match your connector type.
Link coming soon
Replacement display
Must be compatible with your controller and its protocol, not just the same plug.
When it's time for a shop: if you've worked through every step and the problem is still there, take the bike to an e-bike shop. Bring your notes on when it happens, plus the code.