Shimano STEPS error E043: Shimano Steps firmware corruption fault
The drive unit has detected an internal fault in its firmware, meaning part of the software that runs the motor and torque control is no longer valid or has been corrupted. As a result the system cuts motor assist completely, walk assist is disabled, and the speed reading on the display may drop to zero until the firmware is restored. The code cannot be cleared with a normal power cycle and the bike will not run under power.
| Drive system | Shimano STEPS (E5000, E6100, E7000, E8000, EP6, EP801) |
| Severity | Dealer needed |
| Keep riding? | Do not keep riding |
| Typical cost | Expect a dealer firmware reflash around 30-60 EUR, a drive unit replacement at 400-900 EUR depending on model, plus 60-120 EUR labour. |
Likely causes
- Interrupted or failed firmware update via E-Tube, often due to low battery or loose cable during flashing
- Power loss to the drive unit while the firmware was being written
- Internal memory chip fault in the drive unit, typically from age or heat damage
- Moisture ingress into the drive unit causing data corruption
- Incompatible or partial update loaded after a component swap
How to fix Shimano STEPS error E043
- Turn the system off, remove the battery and refit it after 60 seconds, then power on to confirm the error persists.
- Charge the battery to at least 80% before any further steps, since a low battery is the most common cause of failed updates.
- Inspect the junction and motor cables for damaged pins, corrosion or moisture, then dry and reseat them.
- Connect the system to the latest Shimano E-Tube Project software on a PC and attempt a firmware reflash if the drive unit is recognised.
- If E-Tube does not detect the drive unit or the reflash fails, the internal memory is likely unrecoverable without workshop tools.
- Take the bike to a Shimano dealer with proof of purchase so they can reflash or replace the drive unit under warranty if eligible.
Warranty: A genuine firmware or drive unit memory fault within the standard two-year Shimano warranty period is normally covered, while crash damage, water ingress and modifications are excluded.
Typical cost: Expect a dealer firmware reflash around 30-60 EUR, a drive unit replacement at 400-900 EUR depending on model, plus 60-120 EUR labour.
Frequently asked
Can I reset Shimano error E043?
A power cycle will not clear E043 because the fault is stored in the drive unit's firmware. A dealer-level reflash with E-Tube Project or a drive unit replacement is required to remove it.
Is it safe to keep riding with E043 showing?
No. Motor assist, walk assist and the speed signal are disabled, so the bike behaves like an unpowered bicycle. Continuing to ride risks stranding you if the display shuts down mid-ride.
Will Shimano fix E043 under warranty and what will it cost?
If the drive unit is within two years from purchase and there is no sign of water damage or impact, Shimano typically covers the replacement unit and the dealer labour. Out of warranty, budget roughly 500-1000 EUR for a reflash or drive unit swap at a dealer.
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.