Shimano STEPS error W012: Crank fitted in wrong direction
The drive unit has detected that the crank arm is mounted facing the wrong way, so the torque sensor reads incorrect input from your pedalling. As a result the motor assist will not engage, or cuts in and out erratically, and walk assist is unavailable. The bike is still ridable with leg power only, but you have no electrical support until the crank is corrected.
| Drive system | Shimano STEPS (E5000, E6100, E7000, E8000, EP6, EP801) |
| Severity | Warning |
| Keep riding? | Ride with caution |
| Typical cost | A workshop crank refit is typically EUR 30-80 labour, rising to EUR 80-180 if a crank arm or spline replacement is needed. |
Likely causes
- Crank arm refitted on the wrong side after chain or pedal service
- Left and right crank arms swapped at reassembly
- Crankset reinstalled back-to-front after bottom bracket work
- Aftermarket crank arm fitted without checking drive-side orientation
- Chainring or spider mounted in reverse after a deep clean
How to fix Shimano STEPS error W012
- Stop the bike and switch off the system.
- Visually inspect the drive-side crank arm: the chainring must face outward and the arm must seat fully into the drive unit spline.
- If a pedal or chain was just removed, unbolt the crank arm using the appropriate 8 mm Allen key on E5000/E6100 or 10 mm on E7000/E8000/EP6/EP801.
- Refit the crank arm so it sits flush against the drive unit, with the drive-side arrow or stamp facing outward.
- Tighten the crank bolt to Shimano torque spec (typically 40-50 Nm) and refit the chain if it was dropped.
- Power the system on and pedal once: if W012 clears, ride normally; if it returns, the spline or torque sensor is suspect and a dealer must diagnose it.
Warranty: W012 is an assembly error rather than a component fault, so Shimano warranty rarely covers it; a failed torque sensor or drive unit spline inside the two-year warranty period is normally covered as a genuine component defect.
Typical cost: A workshop crank refit is typically EUR 30-80 labour, rising to EUR 80-180 if a crank arm or spline replacement is needed.
Frequently asked
Can I reset shimano error W012?
There is no user reset that clears W012 reliably, because the system checks crank orientation every time it powers on. Switching the bike off and on will not hide a real fitment fault; the code only clears once the crank is physically fitted the right way round and correct pedal input is registered.
Is it safe to keep riding with W012?
You can ride home under leg power alone, since the brakes, gears and lights still work, but motor assist is disabled and walk assist is unavailable. Get the crank corrected at the earliest opportunity, because pedalling a misaligned crank over time can also damage the drive unit spline.
Will Shimano warranty cover a W012 fault?
If a dealer fitted the crank incorrectly, the labour to refit it is usually covered by that dealer rather than by Shimano. If the internal torque sensor or drive unit spline has failed within the two-year warranty window, Shimano normally treats that as a genuine component fault and covers the repair.
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.