004
FAULT CODE
Navien
False Flame (Auto-Reset)
Medium Severity
DIY Check Possible
The boiler has detected a flame signal when not expected. This version auto-resets but if it recurs, the gas valve or PCB needs checking.
Step-by-Step Fix Guide
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Step 1
The boiler should auto-reset
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Step 2
If code 004 recurs frequently, call a Gas Safe engineer to test the gas valve and ionisation circuit
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.