F2 boiler fault on an Ideal boiler: flame loss explained

What F2 means, and how it differs from L2

Ideal boilers use F codes for faults and L codes for lockouts. On Logic boilers, Ideal lists F2 as flame loss: the boiler stopped detecting a flame, usually part way through a heating or hot water cycle. Ideal's fault code FAQ groups it with ignition problems, so the gas supply is the first suspect. Newer Ideal boilers are more likely to show an L code, and Ideal's Logic Code Combi manual identifies L2 as an ignition lockout. Our guide to the Ideal L2 fault covers that code.

Other manufacturers use F2 for different things, and some older or non-Ideal boilers use a similar code for an unrelated fault. Check the brand and model on the front of the boiler before relying on any explanation, including this one. The user guide for your model is the final word on what its codes mean.

If you can smell gas

Do not reset the boiler. Do not use light switches or anything that could spark. Turn the gas off at the meter if you can do so safely, open the doors and windows, leave the property and call the National Gas Emergency Service on 0800 111 999.

Check the gas supply first

Because F2 is about the flame, the gas is the first thing to rule out. These checks are safe and quick.

• Turn on a gas hob ring, if you have one. If it will not light either, the problem is with the supply to the property, not the boiler.
• Check the lever on the gas meter is in the on position, in line with the pipe.
• If you are on a prepayment meter, check there is credit and that any emergency credit has not run out.
• Look at the gas isolation valve on the pipe under the boiler, usually with a yellow handle. It should be in line with the pipe. If it has been knocked or turned during other work, open it fully.
• If the hob works, the meter is on and there is credit, the gas is reaching the house and the cause is more likely to be at the boiler.

In cold weather, check the condensate pipe

Condensing boilers produce water that drains away through a plastic condensate pipe, often run outside to a drain. When that pipe freezes, the water backs up and the boiler shuts down. Depending on the model, it may show a flame-related code or a lockout, and F2 is a common result in a cold snap.

If the pipe is at ground level and easy to reach, you can thaw it with a hot water bottle or warm, not boiling, water, then reset the boiler. Never work at height to get to it. Our guide to a frozen condensate pipe explains how to thaw it safely and how to stop it happening every winter.

Resetting after an F2 fault

Once you have ruled out the gas and the condensate pipe, reset the boiler once using the reset or restart control shown in your user guide. Then watch it through a full heating cycle. If the radiators warm up and the hot water runs normally, the cause was probably a supply interruption.

If F2 comes back, leave the boiler off and book an engineer. A boiler that keeps losing its flame has a fault that another reset will not fix. Our articles on how to reset a boiler and a boiler lockout that keeps returning explain why repeated resets are a bad idea.

Do not take the boiler casing off, adjust the gas valve or clean the burner yourself. Any work on a gas appliance must, by law, be done by a Gas Safe registered engineer.

What an engineer will check

If the supply is fine and the fault keeps returning, the cause is almost always inside the boiler or its flue. An engineer will work through it in a set order rather than swapping parts on a guess.

Getting an F2 fault repaired

Call if F2 returns after one reset, if the gas supply is fine but the boiler will not stay lit, or if you are without heating or hot water and someone in the house is vulnerable to the cold. If the boiler is still under Ideal's warranty, contact Ideal first so the repair does not affect your cover.

Loyal Plumbers has 10 vans covering London and everywhere inside the M25, 24 hours a day, and our boiler repairs are carried out by Gas Safe registered engineers. When you call, tell us the boiler model, the exact code, whether other gas appliances work, whether you are on a prepayment meter and how often the fault has appeared. Our call-out charge is £60, and the engineer explains what they have found and what the repair involves before starting. If the boiler is old and the fault keeps coming back, they can also talk you through whether to repair or replace it.