What W013 / W103 Means
Error W013 on Shimano STEPS E-series motors and W103 on EP8 / EP801 is the most frequently seen Shimano error code — and also the simplest to fix. It is triggered when the bike is powered on while foot pressure is already applied to a pedal. The torque sensor performs a zero-pressure calibration during startup. If it detects force on the pedals at this moment, it flags the calibration as failed and raises W013/W103.
This is a protective design feature, not a hardware fault. In the vast majority of cases, the bike, motor, and all sensors are completely healthy.
Fix — 10 Seconds
- Power the bike off completely.
- Remove both feet from the pedals and stand beside the bike.
- Wait 5 seconds.
- Power on. W013/W103 clears immediately.
If you are on a slope and need to keep a foot on the pedal for balance, hold the bike upright, power on with both feet off the pedals, then carefully place your foot on the pedal after the display shows a clean startup.
When W013/W103 Is Not a Simple Startup Error
If W013/W103 appears during a ride — not just at startup — or if it does not clear after the power cycle procedure above, a genuine torque sensor issue may be present. Check the following:
Chain Tension and Alignment
An incorrectly tensioned chain or a badly worn chainring can transmit mechanical vibration into the motor housing during pedalling, causing the torque sensor to detect phantom loads. Check chain wear and chainring condition.
Crank Arm Condition
A loose or damaged crank arm creates mechanical flex that the torque sensor interprets as rider input. Check that both crank arms are fully seated and tightened to specification.
EP8 vs E8000 Behaviour
Shimano redesigned the torque sensor initialisation on the EP8 motor to be significantly less sensitive to startup pedal position. If you see W013 frequently on an EP8, a firmware update via the E-Tube Project app often resolves it — Shimano has addressed this in several EP8 firmware releases.