Shimano STEPS error E903: Drive unit settings out of sync
The system has noticed that two or more components, such as the drive unit, battery, and display, are running with different settings or firmware versions. To protect the drivetrain, Shimano STEPS usually cuts motor assist or drops it to a very low level and disables walk assist. The bike still pedals as a normal bicycle, so you can roll home under your own effort.
| Drive system | Shimano STEPS (E5000, E6100, E7000, E8000, EP6, EP801) |
| Severity | Dealer needed |
| Keep riding? | Ride with caution |
| Typical cost | A dealer firmware update typically runs €30 to €60 as a stand-alone job, while a warranty replacement of a drive unit or battery is usually €0 to €50 in labour only, and €400 to €900 for the parts outside warranty. |
Likely causes
- Firmware on one unit was updated through E-TUBE PROJECT while the others were left on an older version.
- A replacement battery was fitted that ships with different firmware to the rest of the system.
- A new display or drive unit was installed without re-flashing every component to the same version.
- A previous shop used a diagnostic tool and saved settings to only one unit.
- Mixed generation components, for example an EP6 drive with an E6100 display, that need a common firmware baseline.
How to fix Shimano STEPS error E903
- Power the system off, remove the battery, wait 30 seconds, refit the battery and switch the bike back on.
- Check the firmware version shown on the display against the latest version listed on the Shimano E-TUBE site.
- Connect the bike to a Windows PC running E-TUBE PROJECT using the SM-PCE02 or SM-PCE02A interface.
- Within E-TUBE PROJECT, check every connected unit, then run a full firmware update on all of them in one session.
- Write the settings back to the whole system and run the component test to confirm every unit reports the same firmware.
- Take the bike to an authorised Shimano dealer if the code returns after a clean update, so the diagnostic tool can read each unit's ID.
Warranty: A genuine firmware or component fault inside the standard two-year Shimano warranty is normally covered, while water ingress, crash damage, and mismatch caused by mixing non-genuine parts are usually excluded.
Typical cost: A dealer firmware update typically runs €30 to €60 as a stand-alone job, while a warranty replacement of a drive unit or battery is usually €0 to €50 in labour only, and €400 to €900 for the parts outside warranty.
Frequently asked
Can I reset Shimano error E903?
A simple power cycle will not clear it because the system is comparing live firmware versions, not a stored fault flag. The code only goes away once E-TUBE PROJECT writes matching firmware to every unit in the same session.
Is it safe to keep riding with E903 showing?
The bike still rolls and pedals as a normal bicycle, so a slow ride home on flat ground is generally fine. Avoid steep climbs and busy traffic because motor torque and walk assist are usually cut.
How much does it cost to fix E903 and is it covered?
A dealer firmware update usually runs €30 to €60 and is often free under warranty. If a drive unit or battery has to be replaced, expect €400 to €900 outside warranty, and nothing for parts inside the two-year cover.
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.