E16 on the Velotric (Discover, Nomad, Summit, Fold, Breeze, Triker, T1, GoMad, Tempo) means “Overcurrent in Front Light.” Most likely cause: a damaged light, a pinched light cable, or water in the light plug. Try this first: switch the lights off.
On bikes where the controller powers the lights, a damaged light, a pinched light cable or water in the light plug can cause a fault the controller detects. The bike may still ride, but get it fixed, because a short in the light circuit can damage the controller.
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.
Rechargeable bike light set (USB)
The simplest fix if your built-in light has died: a self-powered light that needs no wiring. To replace the built-in light instead, match the voltage your controller supplies (your manual lists it).
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.