Shimano STEPS error E944: Shifter to drive unit communication fault
The drive unit has stopped receiving a valid signal from the handlebar switch unit, so it flags a communication error. As a result, motor assist switches off, walk assist is unavailable, and the display stays locked on the fault code until the link is restored. The bike still pedals and brakes normally under human power.
| Drive system | Shimano STEPS (E5000, E6100, E7000, E8000, EP6, EP801) |
| Severity | Dealer needed |
| Keep riding? | Ride with caution |
| Typical cost | Allow roughly €20-60 for a replacement harness, €80-200 for a new switch unit, plus €40-90 of dealer diagnostic labour, so most E944 repairs land between €60 and €300. |
Likely causes
- Damaged or pinched cable between the switch unit and drive unit
- Corroded or bent pins inside the switch or motor connector
- Loose connector at the switch end of the harness
- Water ingress in the switch unit after washing or rain
- Internal wiring damage inside the switch from impact or age
- Failed switch unit on the handlebar
How to fix Shimano STEPS error E944
- Power the system off and remove the battery before touching any connectors.
- Trace the cable from the switch on the handlebar to the port on the drive unit and inspect for cuts, kinks, or pinch marks along the frame.
- Unplug the connector at both ends and check the pins for bending, dirt, or green corrosion; clean with isopropyl alcohol and dry fully if needed.
- Reseat both ends firmly until the connector clicks, refit the battery, and switch the system on to test.
- Ride a short loop and confirm assist returns and the code does not reappear.
- If the code returns immediately, the harness or switch unit needs replacement and the bike should go to an authorised Shimano dealer for E-Tube Project diagnostics.
Warranty: Shimano generally treats genuine component failures inside the two-year warranty period as a manufacturer fault, while crash damage, water ingress, and worn or tampered connectors are classed as wear and excluded.
Typical cost: Allow roughly €20-60 for a replacement harness, €80-200 for a new switch unit, plus €40-90 of dealer diagnostic labour, so most E944 repairs land between €60 and €300.
Frequently asked
Can I reset Shimano error E944?
Turn the system off, remove the battery for about 30 seconds, then refit and power on. If the cable and connectors are sound the code clears; if it returns the underlying fault is still present and the reset only masked it briefly.
Is it safe to keep riding with E944?
The motor assist cuts off completely, so the bike is rideable on human power but heavier than usual. Head to a service point without delay and avoid steep climbs where you would normally rely on assist.
How much does it cost to repair and is it covered by warranty?
Most jobs fall between €60 and €300 depending on whether the harness or the switch unit is replaced. Genuine Shimano parts fitted inside the two-year warranty period are normally covered, but the labour and any water- or crash-related damage usually 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.