Bosch error 640: Internal battery error
An internal battery fault reported by the BMS, similar to 603. The battery may shut down, refuse to charge or cut out under load. Restart once; if it returns, the battery has to be tested.
Likely causes
- BMS fault
- Cell imbalance or weak cell group
- Deep discharge damage
- Water ingress or corrosion at the contacts
- Impact damage to the pack
How to fix Bosch error 640
- Switch off, remove the battery, clean the contacts
- Charge fully on the original charger
- Refit and restart
- If the code returns, book a dealer BMS read-out with DiagnosticTool; never open the pack yourself
Warranty: Bosch batteries carry a 2-year warranty (or 500 full charge cycles, whichever comes first); deep discharge from long storage is often classed as user damage.
Typical cost: A replacement Bosch battery is roughly 500-900 EUR/USD.
Frequently asked
Can I reset Bosch error 640 myself?
Only by restarting after a full charge; the BMS cannot be reset by the rider.
Can I keep riding with error 640?
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 640 covered by warranty?
Bosch batteries carry a 2-year warranty (or 500 full charge cycles, whichever comes first); deep discharge from long storage is often classed as user damage.
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.