Brose error 20: Drive unit reports incorrect electrical readings
The Brose controller continuously checks voltage, current and internal sensor signals inside the drive unit. When one of these electrical values falls outside the expected range the controller cuts motor assistance as a safety measure. On screen the rider sees the speed drop to zero, walk assist is disabled, and the display shows error 20 until the fault clears.
| 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 | Dealer diagnostic time typically runs EUR 40-80, a replacement motor harness EUR 60-180 fitted, and a full drive unit replacement out of warranty EUR 700-1200 plus two to three hours of labour. |
Likely causes
- Loose, oxidised or moisture-laden connector between the motor, battery and display harness
- Damaged or chafed motor cable along the down tube or near the swingarm pivot
- Weak battery cell forcing the controller to flag a voltage measurement mismatch
- Internal motor controller fault such as a failed current shunt or Hall sensor
- Impact or crash damage to the motor housing disturbing internal wiring
- Corroded contacts from pressure-washing or riding through deep water repeatedly
How to fix Brose error 20
- 1. Switch the system off using the control panel button and leave it off for at least 10 seconds.
- 2. Remove the battery, inspect the main connector pins for moisture or green corrosion, then dry and reseat the plug firmly.
- 3. Visually trace the motor cable along the frame for chafing, pinching or crushed sections and repair any obvious damage.
- 4. Refit the battery, switch the system back on and ride briefly on flat ground to confirm whether the code clears.
- 5. If error 20 returns immediately, remove the battery again for 5 to 10 minutes to force a full controller reset, then repeat the power-on step.
- 6. When the code still persists after two full reset cycles, take the bike to a Brose-authorised dealer for a diagnostic read-out and possible harness or motor replacement.
Warranty: A genuine component failure inside the motor, controller or original wiring harness within the two-year statutory warranty is normally covered by the manufacturer, while water ingress, crash damage, neglected corrosion and worn connectors are usually excluded.
Typical cost: Dealer diagnostic time typically runs EUR 40-80, a replacement motor harness EUR 60-180 fitted, and a full drive unit replacement out of warranty EUR 700-1200 plus two to three hours of labour.
Frequently asked
Can I reset Brose error 20?
Yes, a full power cycle using the control panel button often clears the code. Switch the bike off, wait at least 10 seconds and switch it back on; if the warning returns immediately the fault is real and needs workshop attention.
Is it safe to keep riding with error 20 active?
No. The controller has deliberately cut assistance because an electrical reading is wrong, so you have no motor support and the drive may behave unpredictably if the fault is intermittent. Ride only on pedal power to the nearest safe place or home.
How much will the repair cost and is it covered?
A diagnostic check usually costs EUR 40-80 and a harness replacement EUR 60-180 fitted, while a full motor replacement out of warranty is EUR 700-1200 plus labour. Bikes under two years old with a confirmed internal component fault are normally covered, leaving only the dealer labour charge.
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.