Overview
The F2 (also shown as FN or LN on some panels) on an Ideal Logic boiler means the boiler has experienced flame loss or an ignition lockout — the burner lit or tried to light but the flame went out or could not be confirmed, so the boiler has locked out for safety. This is a safety shutdown: the control electronics detect the flame is not present when it should be and prevent further attempts to run until the cause is found and corrected. Typical causes include problems with the gas supply or pressure, a malfunctioning or stuck gas valve, a faulty fan or blocked flue preventing safe combustion/venting, wiring or PCB faults, and occasionally blockages in condensate or related systems that interfere with operation. Severity: F2 is potentially serious because it relates to fuel and combustion. It may indicate a simple supply interruption or a more dangerous fault that could allow unburned gas or improper venting. For that reason, most corrective actions that involve internal parts, gas components, or the flue must be carried out by a Gas Safe registered engineer. Some basic, non-intrusive checks and resets can be done by a homeowner to rule out supply issues, but do not remove the boiler casing or work on gas or electrical components yourself.
Troubleshooting Steps
Safety first: If you smell gas (rotten egg smell) or suspect a leak, do not operate electrical switches or the boiler. Turn off the gas at the meter if you can do so safely, evacuate the property, call the gas emergency number for your country immediately and get professional help. If the boiler displays F2 but there is no smell of gas, follow the checks below but do not open the boiler casing or attempt to work on gas valves, fans, or PCB wiring.
Initial homeowner checks (safe, non-intrusive):
1. Check other gas appliances: Try a gas hob, oven or gas fire. If none of your gas appliances work, this points to a mains gas supply issue or meter/isolation problem — contact your gas supplier before calling an engineer. If other appliances work, the issue is likely with the boiler.
2. Check the gas isolation valve to the boiler: Make sure the external gas service cock to the boiler is fully open (usually a lever in line with the pipe). If you have a prepayment meter, check it is in credit.
3. Visual flue check at ground level: If your boiler has a horizontal flue that exits through an external wall, look for obvious blockages near the terminal (birds, leaves, nests, moss). Do not climb ladders or roofs yourself — leave high or roof-level checks to a professional. If you see a clear obstruction, do not attempt to remove anything that requires work at height; call an engineer.
4. Reset the boiler once: Most Ideal boilers have a reset or mode control. Attempt one controlled reset: set the mode control to off, wait 30 seconds, return to the normal position or press the reset button once (follow your user manual for the exact reset procedure for your model). If the boiler restarts and runs normally, monitor it. If F2 returns or the boiler locks out immediately, proceed to professional help.
5. Check condensate pipe (only if accessible safely at low level): In freezing weather a condensate pipe can freeze and block. If you can reach the external condensate discharge at ground level, you may be able to thaw it with warm (not boiling) water. Do not attempt any internal condensate work or remove the condensate trap.
6. Note symptoms: Is the lockout during ignition only, or does the flame drop out while running? Does it happen every time or intermittently? This information helps the engineer diagnose the cause.
Diagnostic points an engineer will check (do not attempt yourself):
1. Gas supply and pressure: A Gas Safe engineer will check incoming mains pressure and the boiler’s gas valve operation. Fluctuating or insufficient gas pressure is a common cause of flame loss.
2. Gas valve: The engineer will test and, if necessary, repair or replace a sticking or faulty gas valve which can fail to deliver steady fuel.
3. Flue and fan: The engineer will inspect the fan and flue system for faults or blockages (including checks for vertical flues that may require specialist access). A failing fan or blocked flue can cause loss of combustion air or dangerous fume build-up and will cause a lockout.
4. Ignition and flame detection circuitry: They will test the ignition electrodes, flame detection (ionisation) circuits, wiring and the PCB to rule out electrical faults causing false flame loss indications.
5. Condensate and pressure-related sensors: On condensing boilers the engineer will check condensate traps/pipes and the pressure/flow sensors that can contribute to lockouts if blocked or faulty.
When to call a professional: Call a Gas Safe registered heating engineer if the reset does not clear the fault, if the fault returns, if you are unable to confirm the gas supply independently, if you find any evidence of flue obstruction you cannot safely clear, or at any sign of gas leaks or hazardous conditions. Do not remove the boiler casing or attempt adjustments to the gas valve, fan, PCB or wiring yourself — these must only be carried out by a qualified Gas Safe engineer. Keep a record of the fault code, any accompanying codes or LED behaviour, and what you observed during your checks to give the engineer the best information for diagnosis.
Helpful Resources
Boiler Manual
Download the official PDF manual for the Ideal Logic Max & Logic Plus Regular Boiler.