E109
FAULT CODE
Potterton
Poor Circulation / Pre-Circulation Fault
Medium Severity
Engineer Required
The boiler has detected insufficient water circulation during its pre-circulation check. Usually caused by airlocks, closed valves, or a failing pump.
Step-by-Step Fix Guide
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Step 1
Check system pressure
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Step 2
Bleed all radiators
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Step 3
Ensure all radiator and isolation valves are fully open
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Step 4
Reset the boiler
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Step 5 Engineer only
If E109 persists, call a Gas Safe engineer to check the pump and system design
Gas Safe Reminder
Work on gas appliances must be carried out by a Gas Safe registered engineer. The steps above cover safe checks a homeowner can perform - any internal component replacement requires a qualified professional. If in doubt, always call an engineer.