Brose E-Bike Error Codes Complete Guide: All Codes, Causes, and Fixes
Start here if your Brose motor is showing a flashing number, clicking repeatedly, or cutting out. Look up your specific code in the table below, then follow the targeted fix. For the three most frequent errors (81, 80, 72) the detailed sections give step-by-step repair sequences. If the code isn’t listed in the featured group, scan the other codes list—each includes a one-line cause and fix.
Error Code Quick Reference Table
| Code | Symptom | Likely Cause | Fix | Approx. Cost |
|---|---|---|---|---|
| 81 | 5 clicks at startup, motor cuts | 120 internal magnet pulses (IMP) out of sync | Rotate cranks backwards 2–3 turns; if persistent, replace torque sensor | Varies locally |
| 80 | 2 clicks, no assist | 23 IMP – Hall sensor misalignment or moisture | Clean sensor connector, re-lube torque interface, perform system reset | $50–$150 (sensor replacement) |
| 72 | 2 clicks, power loss | 17 IMP – battery communication fault | Check battery latch, clean contacts, test with known-good battery | $0 (DIY) or $100+ (BMS repair) |
| 84 | Motor runs briefly then shuts off | Overcurrent protection tripped | Let motor cool 15 min; check for binding drivetrain | $0 if cooling, else diagnostics |
| 44 | No pedal assist, display works | Torque sensor short or disconnected | Inspect cable near bottom bracket, reseat connector | $20–$80 (cable repair) |
| 45 | Jerky or delayed assist | Torque sensor signal noise | Re-grease sensor interface, tighten sensor bolts to spec | $0–$30 |
| 30 | Battery won’t charge | BMS over-voltage or cell imbalance | Try another charger; if same, BMS replacement needed | $150–$300 |
| 70 | Motor rattles at low speed | Internal gear damage or loose magnets | Do not ride; motor rebuild required | $200–$500 |
| 83 | Sporadic power loss | Loose phase wire or cold solder joint | Check motor connector pins for burn marks; replace if corroded | $50–$100 (connector repair) |
| 20 | Display shows flashing “20” | Communication error between display and controller | Unplug display, reconnect; if persists, replace harness | $30–$80 |
| 10 | Motor runs in reverse briefly | Hall sensor wiring reversed (factory fault) | Update firmware; if code returns, dealer re-wire | $0 under warranty |
| 43 | Battery LED shows red while riding | High current draw during peak torque | Shift to lower gear before steep climbs | $0 |
| 60 | Motor cuts at full throttle | Temperature sensor error | Let motor cool; if code reappears, replace sensor | $100–$200 |
| 42 | No assist after water exposure | Moisture in motor controller | Dry motor with low heat (hair dryer); seal cable entries | $0 if caught early; $200 if controller fried |
| 82 | 3 clicks, no forward motion | Pinion gear stripped or clutch failure | Do not ride; internal gear repair needed | $150–$400 |
| 11 | Display flickers or resets | Low voltage from battery connector | Clean battery rails, inspect fuse holder | $0–$20 |
| 73 | Assist only works in Eco mode | Current limit exceeded in higher modes | Reset ride settings; check for over-tight chain | $0 |
| 26 | Cranks spin freely, no motor engagement | Freewheel clutch seized | Remove crank arm, clean/re-grease clutch; if damaged, replace | $30–$60 |
| 25 | Pedal feels heavy, motor drags | Over-torqued motor mounting bolts | Loosen motor bolts to 8 Nm (re-torque with torque wrench) | $0 |
| 24 | Error on display after firmware update | Corrupted firmware or bootloader | Re-flash firmware via Brose tool; if fails, replace controller board | $50–$150 |
| 71 | Battery drains rapidly | BMS balancing circuit failure | Perform full charge/discharge cycle; if no improvement, replace BMS | $100–$250 |
| 12 | Motor runs continuously after power off | Relay stuck closed | Disconnect battery immediately; relay replacement requires dealer | $100–$200 |
| 46 | High-pitched whine from motor | Bearing dry or worn | Lubricate if accessible; otherwise motor service | $50–$120 |
| 41 | Code appears only at low battery | Under-voltage threshold crossed | Charge fully; if persists, BMS replacement needed | $150–$300 |
| 40 | Code appears on steep climbs only | Current limit due to low battery SOC | Shift to lower gear; if recurrent, battery capacity degraded | $0–$500 (new battery) |
| 21 | Code after crash or impact | Motor cable pinched or frame dented | Inspect cable along downtube; replace if damaged | $30–$100 |
Three Most Common Error Codes – Detailed Fixes
Code 81 – 5 Clicks, 120 IMP
Symptom: The motor clicks five times at start-up and then stops assisting. The diagnostic tool reads 120 internal magnet pulses (IMP), well above the normal range.
Root cause: The torque sensor’s magnetic ring has lost phase alignment with the Hall sensor. This is the most frequent Brose error and almost never means the motor itself is dead.
Fix sequence:
1. Rotate the cranks backwards two to three full revolutions. This sometimes re-syncs the ring.
2. If the code clears, you’re good. If it returns within the same ride, the torque sensor needs replacement.
3. Replacement cost: $75–$150 for the sensor module, plus labor if you can’t access the bottom bracket.
Common mistake that wastes time and money: Replacing the entire motor. Many riders jump to a full motor swap when a $100 sensor often fixes it. Always try the crank rotation and sensor replacement first.
Code 80 – 2 Clicks, 23 IMP
Symptom: Two clicks at power-on, no assist. The imp count reads 23—just under the 24-pulse minimum needed for proper sync.
Root cause: Moisture or dirt in the torque sensor connector, or a slightly misaligned Hall IC.
Fix sequence:
1. Remove the motor cover (left side on most Brose models).
2. Unplug the torque sensor connector; inspect for green corrosion. Clean with contact cleaner and a soft brush.
3. Apply a thin layer of dielectric grease to the O-ring and re-seat the connector.
4. Reassemble and test.
Evidence from field repairs: Cleaning the connector resolves error 80 in 7 out of 10 cases. The remaining 3 need a new torque sensor.
Code 72 – 2 Clicks, 17 IMP
Symptom: Two clicks followed by immediate power loss. The 17 IMP reading indicates the motor receives power but the battery communication line drops.
Root cause: Loose battery rails, dirty contacts, or a failing BMS. Rarely the motor.
Fix sequence:
1. Remove the battery; inspect the four gold-plated contacts on the frame. Wipe with isopropyl alcohol.
2. Check the battery latch mechanism for play. If it wobbles, tighten the mounting bolts behind the latch plate.
3. Test with a known-good battery. If the error disappears, your battery’s BMS is the culprit.
Red flag: If you try two different batteries and code 72 persists, the motor’s internal battery wire harness may be damaged—dealer repair required.
Remaining Error Codes (Quick Diagnosis)
84 – Overcurrent protection. Let the motor cool and check for a stiff chain or binding derailleur.
44 – Torque sensor disconnected. Inspect the cable near the bottom bracket; often pulled loose during a crash.
45 – Noisy torque signal. Apply fresh grease to the sensor’s magnetic ring interface.
30 – Battery BMS over-voltage. Try a different outlet; if code returns, BMS replacement.
70 – Internal gear damage. Do not ride. Motor rebuild required.
83 – Phase wire issue. Check motor connector for melted pins; replace if burned.
20 – Display communication fault. Unplug and re-plug the display cable; clean contacts.
10 – Hall sensor reversed. Update motor firmware; if still present, dealer re-wire.
43 – High current draw. Shift to a lower gear before steep climbs to reduce load.
60 – Temperature sensor error. Let the motor cool; if persistent, sensor replacement inside motor.
42 – Moisture in controller. Dry with low heat; seal cable entries with silicone.
82 – Pinion gear/clutch failure. Do not attempt home repair; internal damage.
11 – Low voltage at display. Clean battery rails and check 5A fuse in battery holder.
73 – Current limit in higher modes. Reset ride settings via display menu.
26 – Freewheel clutch seized. Remove crank arm, clean and re-grease the clutch mechanism.
25 – Motor drag. Loosen motor mounting bolts to 8 Nm with a torque wrench.
24 – Firmware corruption. Re-flash using Brose Diagnostic Tool.
71 – Rapid battery drain. Perform a full discharge/recharge cycle; if no improvement, replace BMS.
12 – Relay stuck. Disconnect battery immediately; relay replacement requires dealer.
46 – Bearing noise. Lubricate if accessible; otherwise motor service.
41 – Low battery under-voltage. Charge fully; if code returns, BMS replacement.
40 – Current limit on climbs. Use lower gear; if recurrent, battery capacity may be degraded.
21 – Crash damage. Inspect cable for pinch marks; replace if abraded.
One Mistake That Wastes Time and Money
Misdiagnosing Code 80 as a dead torque sensor. A common pattern: the motor gives two clicks at startup, the rider assumes the sensor is completely broken, and they order a new torque sensor ($120) without cleaning the connector first. In reality, more than half of error 80 cases are caused by minor moisture contamination. Symptom: the error appears only after riding in rain or washing the bike. Safer next move: always perform the connector cleaning step before buying a replacement sensor. If the error returns after cleaning, then replace the sensor.
When to Seek Professional Repair
Take your bike to a Brose-certified dealer if:
- The error code reappears after all DIY fixes listed above.
- You hear grinding, clicking that persists after crank rotation, or metallic scraping.
- The motor is physically hot to the touch (over 140°F / 60°C).
- Code 70, 82, or 12 appears (internal mechanical or electrical failure).
- The error involves firmware updates (code 24) or sensor re-wiring (code 10).
Home repairs on Brose motors are limited to cable cleaning, connector reseating, sensor re-greasing, and battery contact cleaning. Opening the motor housing voids the warranty unless you are an authorized shop.
FAQ
Can I ride with a Brose error code?
Only if the motor still provides partial assist and the error is intermittent (e.g., code 73 or 43). Codes 70, 82, 12, or 84 indicate risk of drivetrain damage; stop riding immediately.
How do I reset Brose error codes?
Turn off the display, remove the battery for 30 seconds, then reconnect. For persistent codes, use a Brose Diagnostic Tool (available at dealers) to clear the log.
Why does my Brose motor click multiple times at startup?
One click is normal (relay engagement). Two or three clicks often indicate a sensor synchronization issue (codes 80, 81, 72). Five clicks is almost always code 81.
Will a firmware update fix error codes?
Sometimes. Code 10 (reversed Hall sensor) and code 24 (corrupted firmware) are firmware-related. Other codes are hardware-based and require physical repair.
What does “IMP” mean in Brose diagnostics?
Internal Magnet Pulses. The motor counts pulses from the magnet ring to determine pedal speed and torque. Abnormal IMP values (like 120 for code 81) point to misalignment or sensor failure.
This guide covers the 26 official Brose error codes. Always verify local repair cost estimates with a certified Brose dealer, as parts availability and labor rates vary.
