H06.64 on a Baxi HP60 / Baxi Assure HP55 High Temperature Monobloc ASHP: HP inverter com Communication error between the outdoor main control unit and the inverter module of the heat pump
Short answer
On a Baxi heat pump, H06.64 means: HP inverter com Communication error between the outdoor main control unit and the inverter module of the heat pump. The heat pump keeps running with some functions stopped. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: HP inverter com Communication error between the outdoor main control unit and the inverter module of the heat pump.
Part involved: PCB communication wiring.
Likely causes:
- If there is a power supply connected to the PCB and to the drive board. Check whether the PCB LED is on or off. If the LED is off, reconnect the power supply wire. If the LED is on, check the wire connection between the main PCB and the drive PCB. If the wire is loose or broken, reconnect the wire or replace it. Fit a new main PCB or drive board.
Is it safe?
| Does the heat pump stop? | Partly |
|---|---|
| Severity | Fault — clears by itself when the condition goes |
| Engineer needed? | Yes |
The heat pump keeps running with some functions stopped.
Resetting itself: yes - system restarts automatically when the cause disappears (may run in degraded/back-up mode meanwhile).
Manual reset: not required once cause removed.
What you can check
- Note the exact code shown on the controller and when it appeared.
- The manual's user steps allow switching the system off and on once to see if the error clears; if the code returns, contact the installer.
- If the code persists or returns, contact a heat pump engineer.
What the engineer will check
- If there is a power supply connected to the PCB and to the drive board. Check whether the PCB LED is on or off. If the LED is off, reconnect the power supply wire. If the LED is on, check the wire connection between the main PCB and the drive PCB. If the wire is loose or broken, reconnect the wire or replace it. Fit a new main PCB or drive board.
Who to ask for: heat pump engineer (controls / sensors).
Certification: Manufacturer-trained heat pump engineer.
What you might notice
Sources
- Installation, user and service manual - Indoor unit ASHP Control ↗ · 7887625 - v04 - 22072025 · page 131 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026