E06.03 on a Baxi HP60 / Baxi Assure HP55 High Temperature Monobloc ASHP: Locking HydrauBackup Locking Hydraulic Backup
Short answer
On a Baxi heat pump, E06.03 means: Locking HydrauBackup Locking Hydraulic Backup. 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: Locking HydrauBackup Locking Hydraulic Backup.
Part involved: power supply / PCB.
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: Remove cause, then acknowledge the error manually on the user interface (engineer).
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).
- 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
- Diagnose per manufacturer service procedure (manual gives description only).
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
- Installation, user and service manual - Indoor unit ASHP Control ↗ · 7887625 - v04 - 22072025 · page 134 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026