H.02-.04 Boiler Fault Code: What It Means on Every Brand

The H.02-.04 fault code appears on 2 brands — Baxi and Remeha — and it does not mean the same thing on each. The same two or three characters can signal a pressure problem on one boiler and an ignition fault on another, so identify your brand first and use the table below to jump to the right page.

Up to: Lockout — engineer likely 2 brands use this code Meaning differs by brand

Which brand is your boiler?

The brand is printed on the front casing. Tap your brand for the full causes, fixes and repair costs.

Brand	What H.02-.04 means	Severity	DIY?
BBaxi	The H.02-.04 fault code on Baxi boilers indicates a parameter error — the boiler's control board has either lost, corrupted, or is unable to read its own stored settings. Full guide →	Lockout — engineer likely	No
RRemehashown as H.02.04	When your Remeha boiler displays H.02.04, it means the main printed circuit board (PCB) — the boiler's central control unit — is unable to read its own stored configuration settings. Full guide →	Engineer may be needed	No

H.02-.04 brand by brand

Baxi H.02-.04

The H.02-.04 fault code on Baxi boilers indicates a parameter error — the boiler's control board has either lost, corrupted, or is unable to read its own stored settings. As a safety measure, the boiler shuts down rather than operate with unreliable configuration data. On Baxi 200 and 400 series models this typically appears as a temporary blocking fault labelled as a parameter error, while on newer Baxi 600 and 800 series boilers the same code can reflect the PCB being unable to read its stored settings at all. In either case the boiler will not fire until the underlying cause is resolved. A single reset attempt is always worth trying first, but if the fault returns the issue almost certainly lies with the PCB itself and will require a Gas Safe registered engineer.

Causes, fixes & costs for Baxi H.02-.04 → · All Baxi codes

Remeha H.02.04

When your Remeha boiler displays H.02.04, it means the main printed circuit board (PCB) — the boiler's central control unit — is unable to read its own stored configuration settings. The PCB acts as the nerve centre of the boiler, receiving signals from every sensor, switch and thermostat and co-ordinating all operating processes. If its onboard memory becomes corrupted or unreadable, the boiler cannot confirm it is set up correctly and will raise this fault to prevent unsafe or incorrect operation. In most cases this presents as a blocking fault rather than a full lockout, but the boiler will not operate normally until the issue is resolved. This code is shared across the wider Baxi Heating Group platform, so you may also encounter it on closely related Baxi and Remeha-badged appliances.

Causes, fixes & costs for Remeha H.02.04 → · All Remeha codes

Frequently asked questions

Is the H.02-.04 fault code the same on every boiler?

No. H.02-.04 means different things on different brands — see the table above. Always identify your boiler's brand (it is printed on the front casing) before acting on any advice about the code.

Can I fix a H.02-.04 fault myself?

Not usually. On every brand listed, H.02-.04 points to a fault that needs a suitably registered engineer to diagnose and repair. A single reset to rule out a transient glitch is reasonable; repeated resets are not.

Who should I call about a H.02-.04 fault?

For gas boilers, a Gas Safe registered engineer — it is a legal requirement for any work on the appliance. If you smell gas at any point, leave the property and call the National Gas Emergency line on 0800 111 999.

General guidance only — not a substitute for professional advice, and not certified by a registered engineer. Any work on a gas appliance must be carried out by a Gas Safe registered engineer. If you smell gas, call 0800 111 999.