Brose error 40: Motor drawing excessive current
The Brose drive has detected that the motor is pulling more current than the controller is designed to deliver under normal load. To protect the motor windings and electronics, the system drops assist to zero or to a very low level until the demand falls back into range. The display shows error 40 and the bike behaves as if assist is switched off until the condition clears or the system is restarted.
| Drive system | Brose Drive (S, T, C - also used by Bulls, Rotwild, Fantic, BH, Trek Allant) |
| Severity | Warning |
| Keep riding? | Ride with caution |
| Typical cost | Dealer diagnostic typically runs €40-80, a replacement controller €150-350, and a complete motor unit €400-800 depending on the Brose model fitted. |
Likely causes
- Rider stamping a high gear against a steep climb with full boost or high assist selected.
- Stuck or dragging brake lever or cable holding the rotor against the pads, forcing the motor to push against the brake.
- Drivetrain binding from a bent hanger, seized jockey wheel, kinked chain, or incorrectly adjusted derailleur.
- Excessively low tyre pressure causing rolling resistance the motor has to overcome.
- Wet mud or grit packed into the motor sprocket area creating a mechanical bind.
- Internal fault in the motor controller or phase wiring (less common, requires bench diagnosis).
How to fix Brose error 40
- Stop pedalling hard and let the motor rest for 30-60 seconds; many overcurrent events clear on their own once load drops.
- Reduce the assist level on the display to Eco or Off, then resume riding gently on the flat.
- Shift to an easier gear before the next hill so the motor does not have to deliver peak torque from a standing start.
- Check both brake levers return fully and the calipers are not rubbing; spin the wheel with the motor off to confirm free rotation.
- Inspect the chain, derailleur hanger and jockey wheels for obvious binding or damage and clear any mud from the motor sprocket cover.
- Switch the system off, wait ten seconds, then power it back on; if error 40 returns immediately the controller or motor needs dealer-level diagnosis.
- Book the bike in at an authorised Brose service centre if the warning repeats on flat ground or at low assist, as the motor or controller may be faulty.
Warranty: A genuine motor or controller failure inside the typical two-year warranty window is usually covered, while damage caused by sustained overload, water ingress, crash impact or unauthorised modification is treated as wear and excluded.
Typical cost: Dealer diagnostic typically runs €40-80, a replacement controller €150-350, and a complete motor unit €400-800 depending on the Brose model fitted.
Frequently asked
Can I reset Brose error 40?
Switch the system off, wait ten seconds and turn it back on. If the warning was triggered by a temporary load spike the code will clear and assist will return, but a code that comes straight back points to a real fault that the rider cannot reset.
Is it safe to keep riding with error 40?
You can ride without assist to the next safe stop, but avoid climbing or hard pedalling because repeated overcurrent trips can overheat the motor windings. Continued high-load riding can turn a temporary warning into permanent damage.
How much will the repair cost and is it under warranty?
A dealer diagnosis is usually €40-80, a controller around €150-350 and a motor €400-800. If the cause is a genuine internal component failure within the two-year warranty period the manufacturer normally covers it; overload and crash damage are not covered.
Related Brose codes
Manuals and video
Official source: Brose error code table, Pedego dealer service guide
Not an official Brose document. Compiled from workshop experience and public service information; details can differ per system version and bike brand.