BoilerFaultCodesYour boiler has detected an issue with the sensor that monitors exhaust gases, and it has shut down for safety purposes.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Flue gas sensor error
What causes this fault?
This fault occurs when the boiler's internal safety sensor detects that the exhaust gases are becoming too hot or if the sensor itself has developed an electrical failure. The most common reason is a buildup of debris or scale inside the main heat exchanger, which prevents heat from being transferred to your water and causes it to escape through the flue instead.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like E16 — no call-out fees, no surprises.
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