E109 High
Your boiler is struggling to move water around the system before it starts the heating process, which is often caused by a blockage or a pump issue.
Technical description: Pre-circulation fault
Typical repair cost: £150-£350 (including labour)
DIY fix possible
Check that your boiler pressure is between 1.0 and 1.5 bar on the pressure gaugeEnsure all radiator valves and boiler isolation valves are fully openGently bleed your radiators to remove any trapped air pockets
Protect yourself from future repair bills
A boiler cover plan would cover faults like E109 — no call-out fees, no surprises.
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Parts commonly replaced
- Circulation pump
- Main heat exchanger (cleaning/flushing)
- Flow temperature sensor
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