Too-high-boot-count-I-O-board-BAS-x on a Worcester Bosch Greenstore LECP ground source heat pump: Too high boot count I/O board BAS x
Short answer
On a Worcester Bosch heat pump, Too-high-boot-count-I-O-board-BAS-x means: Too high boot count I/O board BAS x. The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Too high boot count I/O board BAS x.
Part involved: I/O board / CAN-BUS.
When it shows: Controller executed more than three new starts after 'Check CANbus cable connection'; compressor stops.
Likely causes:
- Controller executed more than three new starts after 'Check CANbus cable connection'; compressor stops.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Fault — needs a manual reset once the cause is fixed |
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: no.
Manual reset: Acknowledgement required; contact installer if it remains.
What you can check
- Read and note the full alarm text and category letter shown on the controller and pass it to your installer.
- Acknowledge the alarm on the control unit once (the manual allows acknowledgement); if it recurs call the installer.
What the engineer will check
- Diagnose per chapter 21: Controller executed more than three new starts after 'Check CANbus cable connection'; compressor stops.
Who to ask for: heat pump installer / controls engineer.
Certification: None specific; electrical isolation required before wiring checks.
What you might notice
Sources
- Installation, Commissioning and Servicing Instructions Worcester Greenstore LECP GSHP (System/Combi 6-11 kW) ↗ · 6 720 806 768 (2013/02) · page 60 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026