H02.04 on a Baxi heat pump: Parameter Error Parameter Error
Short answer
On a Baxi heat pump, H02.04 means: Parameter Error Parameter Error. The heat pump keeps running with some functions stopped. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 2 sources
What it means
On the Assure Split ASHP (AWHP 4.5/6/8 MR + Assure AWHP-IDU 4-8 E)
The manual says: Parameter Error Parameter Error.
Part involved: PCB communication wiring.
Likely causes:
- Restore the factory settings. If the error is still present: change the central unit PCB. PCB settings cannot be read Configure CN1 / CN2 depending on the output of the outdoor unit installed (CNF menu). Check the correct parameter settings.
On the HP60 / Baxi Assure HP55 High Temperature Monobloc ASHP (R290)
The manual says: Parameter Error Parameter Error.
Part involved: PCB communication wiring.
Likely causes:
- Restore the factory settings. If the error is still present: change the central unit PCB.
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
On the Assure Split ASHP (AWHP 4.5/6/8 MR + Assure AWHP-IDU 4-8 E)
- Restore the factory settings. If the error is still present: change the central unit PCB. PCB settings cannot be read Configure CN1 / CN2 depending on the output of the outdoor unit installed (CNF menu). Check the correct parameter settings.
Who to ask for: heat pump engineer (controls / sensors).
Certification: Manufacturer-trained heat pump engineer.
On the HP60 / Baxi Assure HP55 High Temperature Monobloc ASHP (R290)
- Restore the factory settings. If the error is still present: change the central unit PCB.
Who to ask for: heat pump engineer (controls / sensors).
Certification: Manufacturer-trained heat pump engineer.
What you might notice
Sources
- Installation and Service Manual - Air/water 'Split Inverter' heat pump Baxi Assure, Assure AWHP-IDU 4-8 E ↗ · 7762758 - v05 - 19082020 · page 90 · Reviewed 23 September 2026
- Installation, user and service manual - Indoor unit ASHP Control ↗ · 7887625 - v04 - 22072025 · page 127 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026