BoilerFaultCodesYour boiler has shut down because waste water is unable to drain away, likely due to a frozen or blocked external pipe.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: CONDENSATE BLOCKAGE ALARM
What causes this fault?
This fault occurs when the boiler's internal sensor detects that the plastic tray used to collect waste water is full. This usually happens because the external drainage pipe is blocked or restricted, preventing the water from escaping and causing it to back up into the boiler. The unit shuts down as a safety precaution to prevent water from damaging the sensitive electronic components or the burner.
This fault is extremely common during freezing winter temperatures, as the external condensate pipe is prone to freezing and becoming blocked with ice.
DIY fix possible
Locate the plastic pipe leading from your boiler to the outside of your property.Check if the end of the pipe is frozen or submerged in a drain.Carefully pour warm (not boiling) water over the frozen section or use a hot water bottle to melt the ice.
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 8 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Ideal Icos HE is discontinued — time for a new one?
Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
Affiliate links — we may earn a commission at no extra cost to you.