Bosch error 505: Internal fault in the drive unit
Another internal drive unit error, very similar to 500. The motor's electronics have detected a fault that a restart may clear once, but a repeating 505 needs a dealer diagnosis.
Likely causes
- Controller or sensor fault inside the drive unit
- Moisture inside the motor housing
- Loose internal connector after an impact
- Overheating damage
- Firmware fault on an outdated drive unit
How to fix Bosch error 505
- Switch off, remove the battery, wait, refit and restart
- Dry the bike indoors if it has been very wet
- Test ride to see whether the code returns
- If it does, book a dealer to read the error memory with DiagnosticTool
Warranty: Bosch drive units, batteries and displays carry a 2-year manufacturer warranty in most markets; a genuine internal fault within that period is normally replaced free through the dealer.
Typical cost: Drive unit exchange 500-1000 EUR/USD out of warranty; independent repair often 200-400 EUR/USD.
Frequently asked
Can I reset Bosch error 505 myself?
A restart may clear it once, but the fault cannot be reset by the rider if it keeps returning.
Can I keep riding with error 505?
Usually, but with reduced or interrupted assistance and the risk of the system shutting down mid-ride. Ride home carefully or on muscle power alone; do not plan long rides until the cause is found.
Is error 505 covered by warranty?
Bosch drive units, batteries and displays carry a 2-year manufacturer warranty in most markets; a genuine internal fault within that period is normally replaced free through the dealer.
Related Bosch codes
Not an official Bosch document. Compiled from workshop experience and public service information; details can differ per system version and bike brand.