Shimano STEPS Error Code E025 (Non-Genuine Drive Unit / Disconnected Cables): Meaning
TL;DR
E025 = Displayed when a genuine drive unit is not connected or when cables are disconnected; system may not start.
Official next step: Connect a genuine battery/drive unit and check cable condition.
Quick fix (safe DIY first)
- If this appeared after service, re-check every connector the shop may have unplugged.
- Confirm the battery is genuine and properly seated.
- If the bike has any aftermarket electrical device inline, remove/undo it and re-test.
60-second checks (the things that cause repeat codes)
- Any unplugged connectors near the motor cover area?
- Did it start immediately after a firmware update or component swap?
What usually causes E025
- Loose or intermittent connectors (battery mount, motor harness, display/switch).
- Water/corrosion at contacts after rain/washing.
- Firmware/compatibility mismatch after service or a component swap.
- In some cases, an internal sensor or control-unit fault that needs dealer diagnostics.
When to stop DIY (go to a Shimano STEPS dealer)
Go to a dealer if:
– The code returns immediately after a clean restart.
– Assistance cuts in/out while riding (safety issue).
– You see damaged wiring, bent pins, corrosion, or water intrusion.
– The official remedy for the code is “consult an agency/dealer.”
Don’t do this
- Don’t ride with ‘hacked’ speed unlockers or inline dongles; they often trigger system faults.
Related guides (closed-loop)
- Shimano STEPS error codes index: https://jieli-electric.com/shimano-steps-error-codes/
- E-bike error codes hub: https://jieli-electric.com/e-bike-error-codes/
- Speed & power thresholds: https://jieli-electric.com/speed-power-thresholds/
- Laws & Safety Hub: https://jieli-electric.com/laws-safety/