Brose error 12: Battery pack low or fully discharged
The motor controller has detected that the battery state of charge is at or below the minimum working threshold. Pedal assist, walk assist and torque-driven motor support all switch off, and the bike then behaves as a normal unassisted bicycle until the pack is recharged. The display continues to show remaining range or a near-empty battery symbol while the code is active.
| Drive system | Brose Drive (S, T, C - also used by Bulls, Rotwild, Fantic, BH, Trek Allant) |
| Severity | Information |
| Keep riding? | Ride with caution |
| Typical cost | Charging the pack costs nothing, but a replacement Brose-compatible battery typically runs 450 to 900 EUR depending on capacity and frame brand, with dealer diagnostic labour adding 60 to 120 EUR when out of warranty. |
Likely causes
- Battery left in storage for several weeks and self-discharged below the cut-off voltage
- Long ride, headwind or repeated steep climbs drained the pack faster than expected
- Charger not seated properly, faulty mains supply, or dirty contacts on the battery cradle
- Aged battery pack with reduced usable capacity that drops below threshold under load
- Cold weather operation reducing effective capacity below the controller's working range
How to fix Brose error 12
- Switch off the drive system and, if removable, take the battery off the frame.
- Inspect the battery cradle and the contact pins on the pack for dirt, moisture or bent pins; wipe clean with a dry cloth and refit firmly.
- Plug the original Brose charger into a known-good mains socket and confirm the charger LED shows charging in progress.
- Leave the battery on charge until the LED switches to full or green, then refit it on the bike and power the system on.
- Ride normally and watch the state-of-charge reading on the display; if assist returns and the code stays away, no further action is needed.
- If error 12 returns immediately after a full charge, or the pack will not accept charge, the cells or BMS are suspect.
- Book the bike in with an authorised Brose service dealer for bench diagnostics and possible battery replacement.
Warranty: A genuine cell or BMS failure inside the two-year statutory warranty period is normally replaced at no cost, whereas damage from deep discharge during long storage, water ingress or crash impact is treated as owner misuse and excluded.
Typical cost: Charging the pack costs nothing, but a replacement Brose-compatible battery typically runs 450 to 900 EUR depending on capacity and frame brand, with dealer diagnostic labour adding 60 to 120 EUR when out of warranty.
Frequently asked
Can I reset brose error 12?
No manual reset is required. Switching the system off, charging the battery to full and restarting the bike clears the code automatically once pack voltage is back in range. If the code returns straight after a full charge, the pack itself is faulty and the dealer needs to test it.
Is it safe to keep riding with error 12 active?
Yes, the motor assistance cuts off and the bike rides as a normal unassisted bicycle, so riding home without power is safe on flat ground. Avoid long climbs or heavy loads while the code is active, as the controller is signalling a near-empty pack.
How much does the repair cost and is it covered by warranty?
Recharging the pack is free, but a replacement Brose-compatible battery typically costs 450 to 900 EUR fitted, depending on capacity and bike brand. Genuine cell or BMS failure within the two-year warranty window is normally covered at no cost, provided there is no sign of water damage, crash impact or long-term deep discharge.
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.