Shimano STEPS error E239: Accessory power fault in drive unit
The drive unit has detected an electrical abnormality on its accessory power terminal, the port used to feed lights, GPS trackers, USB chargers and similar add-ons. To protect the internal electronics the system typically cuts assist or limits it to a reduced level, and any device powered from that port loses supply. On most displays the code remains shown until the fault is cleared.
| Drive system | Shimano STEPS (E5000, E6100, E7000, E8000, EP6, EP801) |
| Severity | Dealer needed |
| Keep riding? | Ride with caution |
| Typical cost | Dealer diagnostic typically runs EUR 40 to 80, accessory cable repair EUR 20 to 60, and a drive unit replacement if needed usually falls between EUR 600 and 1200 depending on the STEPS model. |
Likely causes
- Third-party accessory drawing more current than the port rating allows
- Damaged, pinched or chafed accessory cable between drive unit and device
- Corroded or wet connector at the accessory port after rain or washing
- Short circuit inside a connected light, GPS tracker or USB device
- Connector not fully seated or locking tab broken so pins are intermittently shorting
- Water ingress into the drive unit housing around the accessory port seal
How to fix Shimano STEPS error E239
- Switch off the bike and remove the battery before any inspection.
- Unplug every accessory from the drive unit accessory port, including lights, GPS units and USB cables.
- Inspect each cable end for bent pins, green corrosion, melted insulation or kinks near the strain relief.
- Dry the port with compressed air if damp, then refit the rubber sealing cap.
- Reconnect the battery, power on and ride briefly to see whether the code clears with nothing attached.
- If clear, plug accessories back one at a time to identify which one trips the fault, and replace that device or its cable.
- If the code returns with no accessory connected, stop DIY work and book the bike in with an authorised Shimano dealer for port and drive unit diagnostics.
Warranty: Accessory port failures caused by third-party devices, water ingress or crash damage are normally excluded, while a genuine internal port fault on a drive unit under two years old is usually covered by Shimano warranty.
Typical cost: Dealer diagnostic typically runs EUR 40 to 80, accessory cable repair EUR 20 to 60, and a drive unit replacement if needed usually falls between EUR 600 and 1200 depending on the STEPS model.
Frequently asked
Can I reset shimano error E239?
Yes, by disconnecting all accessories, removing the battery for a minute, refitting it and powering on. If the code returns with nothing plugged into the accessory port, the drive unit itself needs dealer diagnostics and a plain reset will not fix it.
Is it safe to keep riding with E239?
Only with caution and no accessories connected, since assist may be reduced or cut and any lights powered from the port will go out. Riding at night without lights or under heavy load with intermittent power is not safe.
What does it cost and is it covered under warranty?
A diagnostic at a Shimano dealer usually costs EUR 40 to 80, and any repair follows from what they find. Damage from third-party accessories or water ingress is normally not covered, but a genuine drive unit port failure inside the two-year warranty period is typically treated as a Shimano warranty claim.
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.