H06.67 on a Baxi HP60 / Baxi Assure HP55 High Temperature Monobloc ASHP: ODU return high flow The heat pump return temperature is higher than the flow temperature in the outdoor unit
Short answer
On a Baxi heat pump, H06.67 means: ODU return high flow The heat pump return temperature is higher than the flow temperature in the outdoor unit. 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: ODU return high flow The heat pump return temperature is higher than the flow temperature in the outdoor unit.
Part involved: water flow / pressure.
Likely causes:
- Check the resistance of the two Tw_out - Tw_in sensors Check the position of the two sensors. The water inlet/outlet sensor (TWJn/TW_out) is broken, replace it with a new sensor. The 4-way valve is jammed. Restart the unit again to allow the valve to change the direction. The 4-way valve is broken, replace it with a new valve.
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.
- Read the heating system pressure gauge and report the value to your installer (the manuals quote a minimum of about 1 bar cold).
- Check the filling loop is closed.
- In freezing weather do not leave the system switched off - the manuals warn water faults left unrepaired in winter can let the pump and pipes freeze.
- 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
- Check the resistance of the two Tw_out - Tw_in sensors Check the position of the two sensors. The water inlet/outlet sensor (TWJn/TW_out) is broken, replace it with a new sensor. The 4-way valve is jammed. Restart the unit again to allow the valve to change the direction. The 4-way valve is broken, replace it with a new valve.
Who to ask for: heating / heat pump engineer (hydraulics).
Certification: None beyond heating competence (MCS installer recommended).
What you might notice
Sources
- Installation, user and service manual - Indoor unit ASHP Control ↗ · 7887625 - v04 - 22072025 · page 132 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026