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Brose error 43: Motor Short Circuit Fault

Brose Drive (S, T, C - also used by Bulls, Rotwild, Fantic, BH, Trek Allant)Dealer neededDo not keep riding

The drive unit has detected a short circuit inside the motor and immediately disables motor assist. The display stays powered, but throttle, pedal-assist, and walk-assist all stop working and the rider has to pedal the bike unpowered. Until the error clears, the system behaves like a normal bicycle without electrical support.

Drive system	Brose Drive (S, T, C - also used by Bulls, Rotwild, Fantic, BH, Trek Allant)
Severity	Dealer needed
Keep riding?	Do not keep riding
Typical cost	Out of warranty, expect EUR 400 to 700 for a motor rebuild or EUR 800 to 1200 for a complete Brose drive unit replacement including labour.

Likely causes

Moisture or water ingress into the motor housing or its connectors
Damaged or chafed motor cable between the drive unit and controller
Failed motor phase winding inside the drive unit
Corroded connector pins at the motor or display
Internal PCB fault on the motor control board

How to fix Brose error 43

Switch off the e-bike completely using the control panel power button.
Remove the battery and wait 60 seconds so the system fully discharges.
Reinstall the battery and power the system back on with the control panel button.
Check visible motor connectors for moisture, corrosion, or contamination and dry or clean them if needed.
Inspect the motor cable along the frame for chafing, pinching, or damage.
If error 43 returns after a full power cycle, stop riding and contact your e-bike dealer.
Do not open the motor housing; the drive unit must be diagnosed by a service centre.

Go to a dealer if: A dealer is required when error 43 returns after a full power cycle, because motor disassembly, winding testing, and replacement need Brose-specific tools and a trained technician.
Warranty: A genuine internal motor short circuit within the two-year warranty period is normally replaced at no cost, while water ingress, crash damage, and tampered units are excluded.
Typical cost: Out of warranty, expect EUR 400 to 700 for a motor rebuild or EUR 800 to 1200 for a complete Brose drive unit replacement including labour.

Still stuck? Take a photo of the display and show it to a local e-bike workshop. Bring the bike's system name (e.g. Bosch Performance Line CX) and the exact code; that saves diagnostic time and money.

Frequently asked

Can I reset brose error 43?

Switch the system off with the control panel, wait a few seconds, then power it back on; if the code returns after the reset, the drive unit needs dealer diagnosis. A reset only clears transient faults and will not repair a genuine short circuit.

Is it safe to keep riding?

No, motor assist is cut completely and continued riding can mask a worsening electrical fault inside the drive unit. Ride unpowered only to reach a safe place or transport, then arrange dealer service.

How much will the repair cost?

Within the two-year warranty a genuine motor fault is usually covered in full; out of warranty expect EUR 400 to 700 for a rebuild or EUR 800 to 1200 for a complete drive unit swap including labour.

Related Brose codes

40 · Motor drawing excessive current 41 · Motor drawing excessive current 42 · Internal motor rotation sensor fault 44 · Motor Has Overheated

Manuals and video

Specialized Rider Care knowledge base (manuals)

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.