BoilerFaultCodesWhat the manual says
Manufacturer manualHigh flame indicator. If not lit, check continuity between 4 and 1 on High/Low switch.
What causes this fault?
This occurs when the boiler is commanded to run at its highest heat output but the electrical signal fails to register. The most common reason is a mechanical failure in the high/low switch or a break in the wiring that prevents the system from confirming the flame level. This results in the boiler being unable to modulate its power correctly to meet the demands of your heating system.
This issue is often more noticeable during the first cold spell of autumn when the boiler is required to switch from low-power water heating to high-power central heating.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Avoid the next call-out bill
A cover plan would handle faults like High neon light: no call-out fees, no surprise bills.
Affiliate links. We may earn a commission at no extra cost to you.