Bosch error 606: External battery error
The system has detected a problem with an external battery connection, typically on DualBattery set-ups or a battery connected via an extension cable, or with the wiring to the battery mount. Bosch's own advice is to check the cabling.
Likely causes
- Loose or damaged cable between the battery mount and the drive unit
- Second battery on a DualBattery system not seated or not recognised
- Corroded plug at the battery mount
- Damaged DualBattery Y-cable
- Battery fault on one of two batteries
How to fix Bosch error 606
- Switch off and remove all batteries
- Clean the contacts and check the mount cables and plugs for damage
- On DualBattery: refit one battery at a time and test to see which one triggers the code
- Refit, lock and restart
- If the code persists, a dealer needs to test the mount wiring and batteries with DiagnosticTool
Warranty: Dirty contacts, damaged cables and water ingress are treated as wear or user damage and are rarely covered; a genuine component fault within the 2-year warranty normally is.
Typical cost: A mount cable or Y-cable is about 30-80 EUR/USD plus labour; a faulty battery 500-900 EUR/USD.
Frequently asked
Can I reset Bosch error 606 myself?
Yes, if the cause is a loose plug or dirty contact. A damaged cable has to be replaced.
Can I keep riding with error 606?
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 606 covered by warranty?
Dirty contacts, damaged cables and water ingress are treated as wear or user damage and are rarely covered; a genuine component fault within the 2-year warranty normally is.
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.