BoilerFaultCodesYour boiler is struggling to move water around the system properly, which is causing it to overheat and shut down for safety.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Poor circulation
What causes this fault?
This fault happens because the water inside your boiler is heating up too fast and cannot flow away into your radiators quickly enough. The most common reasons are a pump that has failed or become jammed, or a blockage within the pipework caused by a buildup of sludge and debris.
This fault is frequently seen in autumn when heating systems are switched back on after a long summer break, often revealing a pump that has seized due to inactivity.
DIY fix possible
Check that your boiler pressure gauge is between 1 and 1.5 barEnsure all radiator valves and the external isolation valves under the boiler are fully openGently bleed your radiators to remove any trapped air pockets
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 E109 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Could it be time for a new boiler?
If repair costs are adding up, a new energy-efficient boiler could be the smarter long-term choice.
Affiliate links — we may earn a commission at no extra cost to you.