What Bosch says
Internal time-out error.
Bosch's recommended steps
- Restart the system.
Summarized from Bosch's help center page for error 426, checked October 23, 2026. Follow the link for Bosch's exact wording.
If it keeps coming back
If the code comes back after a restart, have it checked by a mechanic who works on Bosch systems. Bikes Plus has diagnostic tools for Bosch and most other major motor systems.
Write down the code and what you were doing when it appeared. That saves time at the shop.
Make sure it's a Bosch code
Error numbers mean different things on different systems. This page covers Bosch drive systems that show 3-digit codes on Intuvia, Kiox, Purion, Nyon or SmartphoneHub displays. Purion displays may show only the last two digits (for example 03 for 503). The newer Bosch smart system shows 6-digit codes instead; look those up on Bosch's site for now.