Heat pumps · Error codes · Baxi
L7Baxi · HP40 / Baxi Assure HP50 Monobloc ASHP
L7 on a Baxi HP40 / Baxi Assure HP50 Monobloc ASHP: Phase sequence fault (P6/L-group)
Short answer
On a Baxi heat pump, L7 means: Phase sequence fault (P6/L-group). The manual does not say whether the heat pump stops. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Phase sequence fault (P6/L-group).
Part involved: power supply / PCB.
Likely causes:
- Not in the ISM error table; listed only in the wired-controller Modbus code table (value 141). Check supply phase sequence (engineer).
Is it safe?
| Does the heat pump stop? | Not stated |
|---|---|
| Engineer needed? | Yes |
The manual does not say whether the heat pump stops.
Resetting itself: unknown.
Manual reset: Installer: correct cause then power OFF/ON (ISM 13.4).
What you can check
- Note the exact code shown on the controller and when it appeared.
- Check the heat pump's consumer-unit breaker / isolator is on (do not open any panels).
- If the code persists or returns, contact a heat pump engineer.
What the engineer will check
- Not in the ISM error table; listed only in the wired-controller Modbus code table (value 141). Check supply phase sequence (engineer).
Who to ask for: heat pump engineer with electrical competence.
Certification: Qualified electrician / manufacturer-trained heat pump engineer; F-gas if refrigerant circuit is opened.
What you might notice
Sources
- Installer operation manual - Wired controller, Heat Pump air/water 'inverter', Baxi HP40-XX-MB Mono 2 AWHP 4-16MR ↗ · 7799027-00 (web copy 7799027-03 also indexed) · page 30-31 (controller manual, printed) · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026