Bosch error 870: ABS communication error
The ABS unit and the rest of the Bosch system are not talking to each other. The ABS warning lamp stays on and ABS is switched off, but the brakes work as normal brakes and the motor keeps assisting.
Likely causes
- Loose CAN connector at the ABS unit
- Water in a connector
- Damaged cable
- Software mismatch between the ABS unit and the drive unit
- Failing ABS unit
How to fix Bosch error 870
- Full power cycle with the battery removed
- Check the ABS unit connectors
- Dry the bike if it has been wet
- Restart and test
- If the code persists, a dealer must check the harness and software versions with DiagnosticTool
Warranty: The ABS module is a Bosch component with the same 2-year warranty as the rest of the system; damaged sensor cables or bent sensor brackets from crashes are not covered.
Typical cost: Cable repairs 30-80 EUR/USD plus labour; a software session 30-60 EUR/USD.
Frequently asked
Can I reset Bosch error 870 myself?
A restart clears a one-off; a recurring 870 needs a dealer.
Can I keep riding with error 870?
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 870 covered by warranty?
The ABS module is a Bosch component with the same 2-year warranty as the rest of the system; damaged sensor cables or bent sensor brackets from crashes are not covered.
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.