Shimano STEPS error E401: Rear derailleur or motor unit fault
The drive system has flagged an abnormality in the rear derailleur or the motor unit itself. When this code is active, motor assist typically cuts out, the speed reading drops to zero, and walk assist stops responding. The bike can still be pedalled unpowered, but the shifting and torque sensing may be unreliable.
| Drive system | Shimano STEPS (E5000, E6100, E7000, E8000, EP6, EP801) |
| Severity | Dealer needed |
| Keep riding? | Ride with caution |
| Typical cost | Diagnostic fees typically run €30-€80, a rear derailleur or harness replacement €150-€400, and a motor unit repair or replacement €400-€900 depending on the STEPS model. |
Likely causes
- Damaged or corroded rear derailleur wiring or connector
- Water ingress into the motor unit or junction
- Mechanical damage to the derailleur from a crash or impact
- Internal motor unit sensor or board fault
- Loose or bent derailleur hanger
- Worn derailleur causing abnormal current draw on the motor
How to fix Shimano STEPS error E401
- Stop riding and park the bike safely.
- Power off, remove the battery, wait 60 seconds, refit it and switch the system on to clear a transient flag.
- Inspect the rear derailleur cable, motor unit plug and junction for dirt, moisture or impact damage.
- Check the derailleur hanger for straightness and confirm the derailleur moves freely by hand.
- If E401 returns after the restart, do not continue riding with assist engaged.
- Contact the place of purchase or a Shimano dealer for diagnostic, firmware check and component testing.
Warranty: A genuine rear derailleur or motor unit fault inside the two-year Shimano warranty is covered by the manufacturer, while crash damage, water ingress and wear-related failures are excluded.
Typical cost: Diagnostic fees typically run €30-€80, a rear derailleur or harness replacement €150-€400, and a motor unit repair or replacement €400-€900 depending on the STEPS model.
Frequently asked
Can I reset shimano error E401?
A power cycle (battery out, wait 60 seconds, refit and switch on) can clear a transient flag, but if the underlying fault is still present the code returns on the next ride. Treat a returning E401 as a dealer-level issue rather than something a reset will fix.
Is it safe to keep riding with E401?
The bike pedals without assist, but motor cut-outs mid-ride can be hazardous in traffic and the rear derailleur may not be shifting correctly. Ride only the short distance home or to a workshop with assist off, then book a dealer visit.
How much does fixing E401 cost and is it covered by warranty?
Expect €30-€80 for diagnosis, €150-€400 if a rear derailleur or harness is the cause, and €400-€900 if the motor unit itself needs replacement. A genuine component fault inside the two-year Shimano warranty is covered by the manufacturer, while crash and water damage are not.
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.