Shimano STEPS error E814: Inter-unit communication fault detected
The drive unit has lost clean communication with one of the other components on the system, typically the battery, display, switch unit, or rear derailleur. The bike responds by switching the motor assist off or dropping it to a limp mode until the link is restored. The dashboard shows E814 and the system refuses to deliver full power until the fault clears.
| Drive system | Shimano STEPS (E5000, E6100, E7000, E8000, EP6, EP801) |
| Severity | Dealer needed |
| Keep riding? | Ride with caution |
| Typical cost | Budget roughly €30 to €60 for a dealer firmware update, €40 to €120 for a wiring or connector repair, and €400 to €900 if a drive unit has to be replaced. |
Likely causes
- Firmware mismatch between two units after a partial or failed update
- Loose, dirty, or corroded connector between drive unit and battery or display
- Damaged or pinched wiring harness from a crash, overtightened cable tie, or frame rub
- Water ingress in a connector after washing or riding in heavy rain
- Aftermarket or non-genuine unit fitted without proper pairing
- Internal failure of one module preventing it from replying on the CAN bus
How to fix Shimano STEPS error E814
- Switch the system off, remove the battery, wait 60 seconds, refit and power on to clear a transient fault.
- Inspect every connector on the bike: drive unit, battery cradle, display, switch, and derailleur. Unplug, check for bent pins, green corrosion, or moisture, then reseat firmly.
- Recharge the battery to above 50 percent so the firmware updater does not abort mid-flash.
- Connect the bike to E-TUBE PROJECT on a Windows PC or the mobile app and update the firmware on every unit on the system, not just the one that triggered the fault.
- Retry the system. If E814 clears, ride a short loop and confirm full assist returns before normal use.
- Take the bike to an authorised Shimano dealer for a full diagnostic if the code returns, as module-level testing and component replacement require dealer tools.
Warranty: A genuine component fault inside the two-year Shimano warranty period is normally covered, while crash damage, water ingress, and worn cables are not.
Typical cost: Budget roughly €30 to €60 for a dealer firmware update, €40 to €120 for a wiring or connector repair, and €400 to €900 if a drive unit has to be replaced.
Frequently asked
Can I reset Shimano error E814?
A power cycle can clear the code if it was a one-off communication glitch, but the underlying fix is to update every unit's firmware through E-TUBE PROJECT. If the code returns straight away the fault is still present and needs a dealer diagnostic.
Is it safe to keep riding with error E814?
Motor assist may cut out without warning and the walk-assist function is usually disabled, which is risky on hills or in traffic. Ride only as far as the nearest safe stop or workshop and avoid steep climbs.
How much will the repair cost and is it under warranty?
If the cause is a firmware mismatch the dealer charges only for the update, around €30 to €60, and Shimano typically covers genuine component failure inside the two-year warranty. Out-of-warranty repairs rise sharply if a drive unit or battery has to be replaced.
Related Shimano STEPS codes
Manuals and video
Official source: si.shimano.com
Not an official Shimano STEPS document. Compiled from workshop experience and public service information; details can differ per system version and bike brand.