L9
FAULT CODE
Ideal
PCB Fault / Unconfigured
High Severity
Engineer Required
The PCB has an internal fault or has not been configured correctly. L9 is the lockout version of F9.
Step-by-Step Fix Guide
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Step 1
Turn the boiler off at the mains for 10 minutes then restart
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Step 2 Engineer only
If L9 persists, call a Gas Safe engineer — the PCB will likely need replacing or reconfiguring
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.