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Shimano STEPS error codes

Shimano error W020
Battery temperature out of range

The battery is too hot or too cold to use, so it has switched its power off. A bike left in the Florida sun can get there quickly.

Checked against Shimano's own manual: October 23, 2026.

A short list, on purpose. These are the Shimano codes we could confirm in Shimano's own manuals. Most come from Shimano's Japanese manual for the E8080 system and are translated, so follow each source link for Shimano's exact wording. For any code not listed, use Shimano's official lookup at si.shimano.com/error.
Battery hot, swollen, leaking or smells strange? Stop and read battery safety first. If there's smoke, get away and call 911.

What Shimano says

The battery is outside its guaranteed operating temperature. Battery output is shut off.

Shimano's recommended steps

  1. Too hot: leave the battery somewhere cool, out of direct sun, until it cools.
  2. Too cold: bring it indoors until it warms up.

Summarized from Shimano STEPS E8080 user manual (Japanese, translated) (error W020), checked October 23, 2026. Follow the link for Shimano's exact wording.

If it keeps coming back

If the code comes back after a restart, have it checked by a mechanic who works on Shimano systems. Bikes Plus has diagnostic tools for Shimano and most other major motor systems.

Write down the code and what you were doing when it appeared. That saves time at the shop.

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Make sure it's a Shimano code

Error numbers mean different things on different systems. This page covers Shimano STEPS and EP e-bike systems. Codes starting with W are warnings, which clear when conditions improve; codes starting with E are errors, which point to a possible fault. Shimano's E-TUBE PROJECT Cyclist app can read the code from the bike.

All Shimano codes Step-by-step checks