Baxi 600 System 2 H.03.02 code: temporary flame loss

Baxi lists H.03.02 on the Baxi 600 System 2 as “Temporary flame loss.” This means the boiler detected that the burner flame was no longer confirmed during operation and recorded the condition as temporary.

“Temporary” does not mean the code should always be ignored. The boiler may recover and continue, but a code that persists or keeps returning can point to an intermittent problem that needs investigation. The display does not identify one cause and should not be used to justify work on the burner, electrodes, gas valve, flue or wiring.

What temporary flame loss means

When the boiler is operating, its controls must confirm that the expected flame is present. If that confirmation disappears, the appliance responds protectively rather than continuing as though nothing happened. H.03.02 records a temporary flame-loss condition.

The word “loss” describes what the boiler detected, not why it happened. The code alone cannot tell you whether the event was related to gas supply, flame sensing, combustion, the flue, power, controls or another condition. A qualified engineer needs to assess the real pattern if it repeats.

How a temporary H code differs from a lockout

An H code can describe a temporary condition or operating status, while an E code commonly indicates a fault that has stopped operation. That distinction is useful, but it is not permission to dismiss recurring H.03.02 displays.

If the boiler clears the code and resumes normal operation, record when it happened. If heating or hot water is unreliable, the display stays on screen, or the code appears repeatedly, arrange a repair. Repeated temporary events can still cause real disruption and deserve proper checks.

What you may notice at home

The boiler may pause, attempt to continue or return to its normal screen. Radiators may cool, and a separate hot-water cylinder may not be reheated while the boiler is paused. Stored hot water can remain available for a while, so the household symptoms may not appear all at once.

You might hear normal startup sounds followed by the boiler becoming quiet, or notice that the heating works intermittently. Record the timing and which service was being requested. Do not stand over the appliance repeatedly creating heating demands to make the code reappear.

Safe checks before booking repair

Record the exact display

Write down H.03.02 with the punctuation and photograph the screen from the normal user position. Note whether it cleared by itself, how long it remained and whether another code followed.

Check the wider gas supply only at appliance level

If you have another gas appliance, note whether it appears to operate normally, but do not use it if you smell gas or suspect carbon monoxide. Do not inspect the gas meter, open the boiler or adjust any gas control. A working cooker would not prove that the boiler is receiving the correct conditions.

Check heating and stored hot water

Use the normal programmer or thermostat to see whether heating responds. Note whether the cylinder is being reheated. Do not alter installer settings, cylinder wiring or motorised valves.

Note weather and timing

Tell the engineer whether the code appears only during cold weather, during heating, while reheating the cylinder or after a power interruption. These details can show a pattern without assigning a cause.

Should you reset H.03.02?

Because the manufacturer describes it as temporary, the boiler may clear the condition itself. Do not reset it repeatedly. If the Baxi 600 System 2 user guide permits a homeowner reset and the boiler remains stopped, follow that procedure once.

If H.03.02 stays on screen or returns, book a repair. Repeated resets cannot correct an intermittent flame-loss condition and may remove useful evidence.

What not to do

• Do not remove the casing or try to see the burner flame.
• Do not clean, move or replace ignition or flame-sensing electrodes.
• Do not adjust the gas valve, burner, flue or combustion settings.
• Do not test wiring, voltage, resistance or continuity.
• Do not block, disconnect or alter the flue terminal.
• Do not keep resetting the boiler until it happens to remain running.

These are internal gas, combustion and electrical checks. They belong to a suitably qualified Gas Safe registered engineer with the correct equipment.

When professional help is needed

Arrange repair if H.03.02 persists, occurs more than once, or makes heating or cylinder reheating unreliable. Tell the engineer how often it appears and whether the boiler recovers by itself. An intermittent code can be harder to assess without that history.

If the home becomes cold, use safe indoor temporary heating according to its instructions. Keep heaters clear of curtains, bedding and furniture, and never use a barbecue, patio heater or other outdoor appliance inside.

Gas and carbon-monoxide safety

Temporary flame loss does not itself prove there is a gas leak. Nevertheless, act immediately on separate warning signs. If you smell gas, avoid flames and electrical switches, leave the affected area and follow UK gas-emergency guidance.

If a carbon-monoxide alarm sounds or someone develops headache, dizziness, nausea, unusual weakness or confusion, get into fresh air and seek appropriate emergency or medical help. Do not open the boiler to investigate.

What to tell the engineer

Provide the exact Baxi 600 System 2 model, the H.03.02 code, when it appeared, how long it lasted and whether it cleared without intervention. Explain whether radiators or cylinder reheating were affected, whether another code followed and whether the event has happened before.

The engineer can then check the complete operating sequence and safety controls. The correct repair depends on evidence from the installation, not on choosing a familiar cause from a list online.

Quick Answers

What does Baxi 600 System 2 H.03.02 mean?

It means the boiler detected a temporary loss of flame.

Can I ignore it if the boiler starts again?

Record a one-off event, but arrange help if the code persists, returns or makes heating or hot water unreliable.

Does it prove the gas supply is faulty?

No. The code describes the detected condition, not one confirmed cause.

Should I keep resetting the boiler?

No. Allow no more than one reset where the user guide permits it. A returning code needs professional investigation.