BoilerFaultCodes S.46 Low Warning
Your boiler has noticed an unstable flame when running at its lowest setting and is operating at a restricted level to prevent a complete breakdown.
Monitor it
This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.
Technical description: Comfort protection: Minimum load, loss of flame. Comfort protection mode for flame loss at minimum load is activated.
What causes this fault?
This fault occurs when the boiler struggles to maintain a steady flame while running at its lowest power level. The most common cause is a dirty or worn-out sensing probe that can no longer accurately detect the fire, or an incorrect mix of gas and air preventing a consistent burn.
Typical repair cost £80-220 (including labour)
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like S.46 — no call-out fees, no surprises.
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