Shimano STEPS · Communication
E020 Shimano STEPS error code E020
Communication error between battery and drive unit
Per manufacturer documentation
Note
Meaning may depend on model, display and firmware – verify with the manual of the exact type.
Possible causes
General, component-based causes – not a manufacturer-specific statement.
- Harness/connector fault (break at handlebar, corrosion)
- Incompatible component/firmware
- Component supply fault
Safe test steps
- Unplug connectors, check pins and corrosion.
- Compatibility (protocol UART/CAN, firmware).
Workshop reference values
- Voltages on communication lines depend on the protocol; measure only with the manufacturer pinout.
Repair approach
- Repair harness/connector; use compatible component/firmware.
Tools needed
- Digital multimeter (CAT III, fused inputs)
- Contact cleaner, dielectric grease
- Manufacturer dealer diagnostic tool/software (if available)
Safety
- Power down (remove the battery) before unplugging connectors. Never apply pack voltage to data wires.
This information does not replace manufacturer service documentation. Work on batteries and high-voltage parts only with the appropriate expertise.
Related fault codes
W010Drive unit temperature is higher than normalW011Travel speed cannot be detectedW013Torque sensor initialisation was not completed normallyW032Electronic derailleur may have been replaced with a mechanical oneE010System error detectedE013Abnormality in drive unit firmwareE014Speed sensor may be installed in the wrong positionE021Connected battery conforms to the standard but is not supported