Brose Drive C/Drive C mag/Drive S Mag — Error Code 04
Reviewed by certified eBike technicians · Last updated July 21, 2026
Quick Answer
04 on Brose = Cadence sensor error — pedal cadence signal lost or reading outside expected range
Severity: Check soon — cadence sensor issue · Limited riding OK, diagnose soon
Error 04 on your Brose indicates: Cadence sensor error — pedal cadence signal lost or reading outside expected range.
Check soon — cadence sensor issue — Cadence sensor error — pedal cadence signal lost or reading outside expected range
Symptoms
- Error 04 on Brose display; pedal assist does not engage or delays significantly; motor may only respond to throttle; assist level changes have no effect on pedal assist
Common Causes
- Cadence sensor ring on bottom bracket misaligned or damaged
- Cadence sensor magnet cracked or shifted from impact
- Sensor wire damaged where it exits the motor housing near bottom bracket
- Mud or debris blocking the cadence sensor pickup
- Sensor connector loose or corroded at motor controller
- Cadence sensor internal Hall element failure
Fix Steps
Step 1: 1. Check the cadence sensor ring around the bottom bracket — should spin freely with the cranks
Step 2: 2. Look for cracks or missing magnets in the sensor ring — Brose uses a 12-magnet ring
Step 3: 3. Clean any mud or debris between the sensor ring and pickup
Step 4: 4. Check gap between sensor ring and pickup — should be 1-3mm, adjust if wider
Step 5: 5. Inspect the sensor wire from bottom bracket to motor housing for cuts or abrasion
Step 6: 6. Unplug and replug the cadence sensor connector at the motor — check for corrosion
Step 7: 7. Spin cranks by hand and verify cadence reading on display — should show RPM
Step 8: 8. If cadence still reads 0: replace cadence sensor assembly (~$25-40 from Brose dealer)
Related Error Codes
Always disconnect the battery before inspecting wiring.