E9
FAULT CODE
Worcester Bosch
Overheat Fault
High Severity
Engineer Required
The boiler's safety thermostat has detected dangerously high temperatures and triggered a lockout. Usually caused by poor circulation, low water pressure, or a failing pump.
Step-by-Step Fix Guide
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Step 1
Turn off the boiler and allow it to cool for at least 30 minutes
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Step 2
Check system pressure and repressurise if below 1 bar
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Step 3
Bleed radiators to remove airlocks
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Step 4
Reset the boiler once
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Step 5 Engineer only
If E9 returns, call a Gas Safe engineer — the pump or temperature sensors may need attention
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.