Error E09

Safety first

- If you smell gas: do not operate the boiler or electrical switches. Turn off the gas supply at the meter or emergency isolation, ventilate the area and call the gas emergency number and a Gas Safe engineer immediately.

- If you are not comfortable working around gas appliances or electricity, do not open the boiler; call a Gas Safe engineer.

- Do not repeatedly reset the boiler if the fault reoccurs — repeated resets can mask a dangerous condition and may cause further damage.

Initial checks a homeowner can do

1. Note the conditions when the code appears: on start-up, during operation, after a power cut, after servicing, or intermittently.

2. Try a simple reset: locate the reset button on the front panel and press and hold for the time recommended in your manual (typically 1–5 seconds) until the unit attempts to restart. Wait to see if the code returns.

3. Check the gas supply: confirm other gas appliances (hob, oven) are working and that any gas isolation valve to the boiler is open. If you use a prepayment meter, confirm there is credit.

4. Check mains power and timers: ensure the boiler display is powered, fuses in your consumer unit are OK, and any external controls or programmers are calling for heat correctly.

5. Record boiler pressure and basic symptoms: note the pressure gauge reading and whether hot water or heating is affected.

If the fault persists (safe visual checks only)

1. Power down: If you are competent and choose to proceed with a visual inspection, switch off electrical supply to the boiler at the isolator or consumer unit and turn off the gas at the external isolation valve. Only do this if you understand how to safely isolate the appliance.

2. External visual inspection: without removing internal covers, look for obvious damage to external cables entering the boiler, signs of water ingress or corrosion around glands, or burnt/charred wiring that might be visible from the access point.

3. Reboot and test: restore power and gas, try another reset and observe whether E09 returns. If it was a transient fault it may have cleared.

Internal checks and diagnostics (only for qualified persons)

- The gas valve connection and wiring harness are inside the boiler casing and are part of the gas control system. If you are not Gas Safe qualified do not remove internal panels, touch wiring or attempt to repair the gas valve.

- A competent engineer will isolate the appliance, remove the front cover, check the gas valve connector is correctly seated, inspect the connector and wiring for corrosion, damage or burning, and check continuity of the cable and integrity of the crimps.

- The engineer may also test for correct communication between the PCB and the gas valve, and check for any related PCB fault codes or indications. If wiring is OK the fault may be the valve or the PCB, which require professional replacement/repair.

When to call a professional

- Call a Gas Safe registered engineer if the E09 code does not clear after a reset and the simple checks above, if you find any damaged wiring, if the fault is intermittent, or if you have any doubt about safety.

- Provide the engineer with details: model (Baxi 600 Combi), error code E09, when it occurs, any recent work or power/gas interruptions, and anything you observed during visual checks.

Important reminders

- Do not attempt to repair or replace the gas valve, internal wiring or PCB yourself unless you are Gas Safe qualified. Work on gas valves is hazardous and illegal if not carried out by a qualified engineer.

- If there is any sign or smell of gas, isolate supply, ventilate, and call the emergency gas service immediately.

- If the fault clears after a reset but returns later, book a professional inspection rather than relying on repeated resets.