E.04-.12
FAULT CODE
Baxi
False Flame Signal (200/400)
High Severity
Engineer Required
On Baxi 200/400 boilers, E.04-.12 indicates a false flame signal is present — ionisation detected without a flame, or gas/air ratio too high (CO2 too high).
Step-by-Step Fix Guide
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Step 1
Turn off the boiler at the gas isolation valve
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Step 2 Engineer only
Call a Gas Safe registered engineer immediately
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.