303
FAULT CODE
ATAG
PCB Error
High Severity
Engineer Required
The main Printed Circuit Board has detected an internal fault.
Step-by-Step Fix Guide
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Step 1
Turn off at mains for 10 minutes, then restart
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Step 2 Engineer only
If fault persists, call a Gas Safe engineer — the PCB may need replacing
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.