Bosch error 426: Internal time-out error
A component did not answer within the expected time during start-up or operation. It is usually a one-off glitch: the system restarts and the code is gone. When it keeps returning it points to a marginal connection or a failing component.
Likely causes
- A momentary hiccup during system start-up
- Battery contacts briefly interrupted on a bump
- Loose display on its holder
- Marginal connector in the harness that only fails when cold or wet
- Component software mismatch after an update
How to fix Bosch error 426
- Switch the system off, wait 10 seconds, switch on again
- Take the display off and refit it firmly; clean the holder contacts
- Remove and refit the battery, making sure it locks
- Ride a short test loop; if the code stays away, no further action is needed
- If it keeps returning, a dealer needs to find the intermittent connection 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: Usually free; a recurring case is typically a cable or contact repair of 30-100 EUR/USD.
Frequently asked
Can I reset Bosch error 426 myself?
Yes. Switch off and on again; that clears it in most cases. Only a recurring 426 needs a dealer.
Can I keep riding with error 426?
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 426 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.