Shimano STEPS error E031: Chain tension and crank position fault
The drive unit has flagged that the chain tension is not correctly set or that the crank arm is not seated in the proper position on the axle. As a safety response, the motor typically cuts or heavily limits assist until the mechanical condition is corrected. Walk assist is usually disabled as well, and the error returns each time the system is powered on.
| Drive system | Shimano STEPS (E5000, E6100, E7000, E8000, EP6, EP801) |
| Severity | Dealer needed |
| Keep riding? | Ride with caution |
| Typical cost | A chain tension and crank torque service typically runs 20-60 EUR; a new Shimano chain is 15-45 EUR and a replacement crank arm around 30-90 EUR plus 40-80 EUR fitting labour if replacement is required. |
Likely causes
- Chain installed or replaced without correct tension adjustment
- Crank arm loose or not torqued to spec on the spindle spline
- Crank arm fitted in the wrong rotational position on the axle
- Worn or stretched chain causing excess slack under load
- Recent drivetrain service where components were not reassembled correctly
- Chainring or chainring guard fitted incorrectly and interfering with the crank position sensor
- Belt-drive conversion or aftermarket chainring not matched to the drive unit
How to fix Shimano STEPS error E031
- Power off the system and remove the battery before any mechanical work.
- Inspect chain tension by pressing up on the chain at the midpoint of the chainstay; it should deflect roughly 10-15 mm.
- Check both crank arm pinch bolts and the main spindle bolt, torquing to the Shimano spec listed on the crank cover.
- Confirm the drive-side crank is fully seated on the spline and the crank pair sits at 180 degrees with no gap at the axle.
- Reinstall the battery, power the bike on, and check whether the code clears with a short test ride.
- If E031 returns immediately, stop riding and have a dealer run the Shimano diagnostic to read the drive unit data.
- Book a service appointment for chain tensioning, crank re-installation, or replacement of any worn drivetrain parts found.
Warranty: Mechanical setup issues such as chain tension or crank fitment are treated as maintenance and are not covered, while a genuine sensor or drive unit fault inside the two-year Shimano warranty period is normally replaced at no cost.
Typical cost: A chain tension and crank torque service typically runs 20-60 EUR; a new Shimano chain is 15-45 EUR and a replacement crank arm around 30-90 EUR plus 40-80 EUR fitting labour if replacement is required.
Frequently asked
Can I reset shimano error E031?
You can attempt a reset by switching the system off, removing the battery for around 30 seconds, and powering it back on. The code will reappear on the next ride if the chain tension or crank position is still wrong, so the underlying mechanical issue must be corrected.
Is it safe to keep riding with E031?
Riding with E031 active is not recommended because the motor has cut assist to protect the drivetrain. Continuing to pedal under load with a loose chain or misaligned crank can damage the chainring, crank, or drive unit internals.
How much will the repair cost and is it covered by warranty?
A basic chain tension and crank position check usually costs 25-60 EUR and is treated as routine service, not warranty work. If a dealer identifies a genuine component fault inside the two-year Shimano warranty, the affected part and labour are covered.
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.