If your Baxi boiler shows H.02.03, Baxi’s official description is: “Configuration settings (CN1, CN2) not entered correctly.” The boiler has detected that technical configuration information identified as CN1 and CN2 is incorrect.
These are not ordinary homeowner temperature or timer settings. Do not enter installer menus, copy values from another boiler, perform a factory reset or remove the casing. Record the exact code and arrange professional repair if it remains.
What does Baxi H.02.03 mean?
A boiler needs the correct technical configuration for its model and control system. H.02.03 reports that the CN1 and CN2 configuration settings were not entered correctly. The code tells an engineer what state the boiler has detected; it does not provide a safe do-it-yourself correction.
Incorrect configuration can affect the way the boiler operates. The correct information must come from the manufacturer’s technical documentation for that exact appliance, not a forum post, another boiler or a guessed sequence.
Which Baxi boilers list H.02.03?
Baxi includes H.02.03 in its Combi & System 2 error-code group. The listed models are the Baxi 200, 400, 600 and 800 Combi 2, Baxi Assure 500 Combi 2, Baxi 600 and 800 System 2, and Baxi Assure 500 System 2.
Confirm the exact product name from information on the outside of the boiler and use its matching user guide. Similar control panels do not guarantee identical technical settings.
What are CN1 and CN2?
CN1 and CN2 are the terms Baxi uses in the official fault description for the required configuration settings. For homeowners, the useful distinction is that these are technical values rather than the room temperature, heating schedule or hot-water temperature you normally choose.
Do not search for universal CN1 or CN2 values. Model-specific configuration belongs with an engineer who can identify the appliance correctly and use current Baxi information.
H.02.03 compared with H.02.02
The two codes are closely related but not interchangeable. H.02.02 means the boiler is waiting for configuration settings to be entered. H.02.03 means those settings were not entered correctly.
Copy every character and dot from the display. The difference helps an engineer understand whether the boiler is waiting for information or rejecting information as incorrect.
Safe checks you can make
- Write down H.02.03 exactly.
- Confirm the full boiler model from its external product details.
- Note whether heating, hot water or both are unavailable.
- Record any other code shown before or after H.02.03.
- Think about whether installation, servicing, a recent repair or a power interruption preceded the message.
- Check ordinary room controls are on their usual user settings.
Do not remove the casing, inspect CN1 or CN2 connections, alter parameters, copy configuration values, move connectors, test wiring or voltage, replace the PCB, or enter commissioning menus. Those are not homeowner checks.
Why might the code appear?
The public Baxi description confirms incorrect configuration settings but does not name one failed part or one universal cause. Recent work can be useful context, but it does not prove who or what caused the code. A professional must assess the system before drawing conclusions.
Tell the engineer when H.02.03 first appeared and whether the appliance or controls were recently changed. This may help them focus the correct model-specific checks while keeping you safely outside the boiler.
Should you reset H.02.03?
Baxi reset controls vary between models. If the exact user guide provides a homeowner reset instruction for this situation, follow it once. If H.02.03 remains or returns, do not continue resetting.
Baxi says frequent lockout indicates a fault and that the installer or service engineer should be contacted. A reset cannot make incorrect technical configuration values correct.
Can you use the boiler?
Follow your model’s user guide and do not force operation. If normal heating or hot water is unavailable, leave the technical controls untouched and arrange repair. If the boiler behaves unusually or another safety warning appears, switch it off using the normal user control where safe.
If you smell gas, suspect carbon monoxide, feel unwell or a carbon-monoxide alarm sounds, treat that as an emergency. Avoid electrical switches and naked flames where gas is suspected, move to fresh air where appropriate and contact the gas emergency service.
What will an engineer check?
An engineer will verify the model and code, review recent work and use the correct Baxi technical information to assess the CN1 and CN2 configuration and the boiler’s control system. They can then correct the underlying issue safely.
H.02.03 is preventing normal operation?
Book a fixed-price boiler repair aimed at fixing the fault, with the booking price clear before the visit.
Quick answers about Baxi H.02.03
What does H.02.03 mean?
It means CN1 and CN2 configuration settings were not entered correctly.
Are CN1 and CN2 normal thermostat settings?
No. They are technical boiler configuration terms.
Can I copy settings from another Baxi boiler?
No. Configuration is model-specific and must not be guessed or copied.
Is H.02.03 the same as H.02.02?
No. H.02.02 is waiting for settings; H.02.03 says the settings are incorrect.
Who should fix H.02.03?
A suitably qualified Gas Safe registered engineer using current Baxi information.