High
B.(5) on Potterton Kingfisher 2 RS60, RS80, RS100

Your boiler is failing to stay lit because the safety mechanism thinks it is unsafe to keep the gas flowing.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

What the manual says

Manufacturer manual

Main burner fails to light and pilot is extinguished when pressure on the control knob is released - Failure of thermocouple, power unit or latching mechanism.

Shared across the Kingfisher 2 range
This code is shared by the boilers in this range, which use the same control board. It may not be printed in this exact variant’s manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

What causes this fault?

This fault occurs when the boiler's safety circuit fails to detect a constant, healthy pilot flame, causing it to shut off the gas supply for safety. The most common reason is a worn-out thermocouple that can no longer generate the tiny electrical current needed to hold the gas valve open, though it can also be caused by a faulty magnetic latch within the valve itself.

This issue is frequently noticed during the first cold spell of autumn when the boiler is switched back on after being idle over the summer, as debris can build up around the pilot light.

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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All 17 fault codes on the Kingfisher 2 RS60, RS80, RS100

Seeing a different code? Every code this model can display, in one place.

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