L6 on an Ideal boiler is a false flame lockout. The appliance is receiving a flame signal at a point in the cycle when there should be no flame.

This is one to leave alone and get an engineer to. It is the same family of fault as a Vaillant F27 or a Worcester Bosch FA.

What L6 actually means

The boiler expects the flame signal to disappear when the burner is off. If it does not, the appliance cannot tell whether there genuinely is a flame or whether the sensing circuit is lying to it.

Because one of those possibilities involves gas burning when it has not been asked for, the boiler treats it as serious and locks out.

What you can safely check yourself

Nothing. The components involved are inside the appliance and this is Gas Safe work.

Turn the boiler off at the switch and call an engineer.

When to stop, and why

What causes it beyond the simple checks

The manufacturer’s chart has the engineer check the condition of the ignitor and the spark generator and replace as required, and check the routing and integrity of the internal boiler wiring. A contaminated or damaged electrode holding a false signal is the usual finding, but it is not assumed.

How Vantage can help

We are Gas Safe registered under 956889 and cover Hertfordshire, Bedfordshire and Cambridgeshire, with an emergency line answered 24 hours a day. Call us on 01462 506374. See also boiler repair and boiler servicing.

Frequently asked questions

Can I use the boiler with L6 showing?

No. Turn it off and call a Gas Safe engineer.

Is L6 dangerous?

The lockout is the boiler being safe. The reason behind it needs diagnosing rather than clearing.

Is it usually just the ignitor?

Often, yes. The manufacturer’s own chart starts there. But it cannot be assumed without checking.

Related fault codes

Other Ideal codes: L1 · L2 · LC · F1 · F2 · F3 · F4 · F5 · F6 · F7 · F8 · F9 · all boiler advice. See also boiler repair. The same fault on other makes: Vaillant F27 · Worcester Bosch FA.

In Ideal’s own words

Ideal use different code sets across their ranges and generations. The definition above comes from The Ideal installation and servicing guide. If your boiler is a different model and the code behaves differently, check the manual for your appliance or ring us and we will tell you what it means on your unit.

When to call an engineer

If the checks above have not cleared it, the next steps are engineer work and the boiler should not be reset repeatedly in the meantime. Call Vantage Plumbing and Heating on 01462 506374. We are Gas Safe registered under 956889, the line is answered by a person at any hour of any day, and you get a price before anyone starts.

Need help today?

Call and speak to a person, any hour, any day of the year. Get a fixed price quote or call 01462 506374.