L2 on a Worcester Bosch Bosch Compress 2000 AWF: Alarm table: DC bus high voltage protection / Troubleshooting table: High voltage BUS protection of the inverter module
Short answer
On a Worcester Bosch heat pump, L2 means: Alarm table: DC bus high voltage protection / Troubleshooting table: High voltage BUS protection of the inverter module. 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: Alarm table: DC bus high voltage protection / Troubleshooting table: High voltage BUS protection of the inverter module.
Part involved: inverter DC bus.
When it shows: DC bus high voltage protection.
Likely causes:
- High DC bus voltage (see L0 check list).
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Fault — clears by itself when the condition goes |
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: yes.
Manual reset: Manual 13.2: switch the unit off and on again to reset the safety device; if reset fails contact dealer. Manual 11.4 warns repeated resets can cause irreversible damage.
What you can check
- Read and note the full code (and sub-code) shown on the controller and pass it to your installer.
- Manual 13.2: one off/on restart may be tried; if the code returns, stop and call an engineer - repeated resets can damage the unit.
What the engineer will check
- Check supply and inverter per L0 list.
Who to ask for: heat pump installer / electrician.
Certification: Electrical work to BS 7671 by competent person.
What you might notice
What owners and engineers report
1 owner and engineer report mentions this.
- Keeps stopping / cutting out on the Bosch Compress 2000 AWF (R32 all-in-one monobloc): 1 report
Sources
- Installation and operating instructions Compress 2000 AWF CS2000AWF 4-30 R-S/T ↗ · 6721859133 (2025/10) · page 129; 139 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026