501
FAULT CODE
ATAG
No Flame Detected
Medium Severity
Engineer Required
No flame signal detected during operation. Separate from code 133 (ignition failure) — this may occur if the ionisation signal is lost during burner operation.
Step-by-Step Fix Guide
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Step 1
Check gas supply
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Step 2
Reset once
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Step 3 Engineer only
Call a Gas Safe engineer if fault persists — the ionisation electrode may need cleaning or 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.