Error 5 long flashes, 4 quick flashes, 5 second gap, 5 long flash, 4 quick flashes

Safety precautions:

1) If you smell gas or suspect a gas leak, immediately: do not operate electrical switches, extinguish naked flames, open windows and doors, turn off the gas at the meter if you can do so safely, evacuate the property and call the national gas emergency number. Do not attempt any repairs.

2) If you have any doubt about safety, stop and call a Gas Safe registered engineer.

3) Do not remove the boiler casing or attempt repairs to gas components, electrodes, sensors or the PCB yourself.

Initial checks a homeowner can safely do:

1) Note the exact flash sequence and any numeric cause code shown in the information menu (press the spanner/return or info button on the boiler — record any 3‑digit cause code). This information is useful for the engineer.

2) Ensure the boiler has mains power and the programmer/room thermostat is calling for heat; confirm other house gas appliances are working to verify gas supply (unless you smell gas — then follow emergency instructions above).

3) Check boiler pressure at the gauge: it should typically be around 1–1.5 bar when cold. Very low pressure can cause faults. Repressurise only if you know how and the system is intact.

4) Check for obvious external problems: visible water leaks around the boiler, frozen or blocked condensate pipe (in winter), blocked air intake or flue terminal outside, or anything that might have been disturbed recently (servicing, power cuts, storms).

5) If the condensate pipe is frozen, gently thaw with warm (not boiling) water; do not use open flames.

Safe reset and observation steps:

1) Perform a single controlled reset: follow the boiler’s reset procedure (turn the control knob anti‑clockwise to the reset position or press the reset button as per the manual). Wait for the boiler to attempt a restart.

2) After resetting, wait and observe for at least 10–15 minutes to see if the lockout returns. Do not perform repeated rapid resets more than once or twice — repeated resets can mask a dangerous fault and may cause further damage.

3) If the boiler restarts and runs normally, monitor it closely for the next 24–48 hours. If the fault reoccurs, do not ignore it; record the conditions when it happens (time, whether heating or hot water was in use, outside temperature, recent power cuts or maintenance).

When to avoid further DIY and call a professional:

1) If the error returns after a reset, or if you recorded a cause/code that indicates flame, valve or sensor faults, contact a Gas Safe registered engineer. The fault may require testing and replacement of ignition electrodes, ionisation probe, gas valve or control PCB and must be done by a qualified technician.

2) If you find any of the following during your checks: smell of gas, visible water leak from the boiler or pipework, persistent loss of flame detection, repeated lockouts after reset, or any internal component appearing burnt/damaged, stop and call a Gas Safe engineer.

Information to give to the engineer and what they will likely do:

1) When you call, be ready to provide the exact flash sequence and any cause code you recorded, when the fault started, any recent power outages or servicing, whether the fault occurs on CH, DHW or both, and whether you smell gas or see leaks.

2) The engineer will run diagnostic checks, view stored cause codes, and perform safe tests on the ionisation/flame detection circuit, ignition electrodes, gas valve operation and PCB communications. They may replace the ionisation probe or ignition electrode, repair or replace the gas valve, replace a faulty PCB/module, or repair wiring/connectors, depending on the diagnosed fault.

Final notes and warnings:

1) Repeated resets are not a solution. Lockouts related to flame detection or gas valve tests indicate safety systems doing their job; they need proper rectification.

2) Only a Gas Safe registered engineer should work on gas valves, ignition systems, sensors and the boiler internals. If the boiler is under guarantee or service plan, contact the manufacturer or your service provider and provide the fault details you recorded.

3) Keep a note of the fault sequence, cause code and any actions you took — this speeds up the engineer’s diagnostic process and helps ensure the correct repair is made.