BoilerFaultCodesYour boiler has shut down because the exhaust gases are getting too hot, which is a safety feature to prevent internal damage.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: High flue gas tempurature
What causes this fault?
This fault occurs when the internal sensors detect that the exhaust gases leaving your boiler have reached a dangerously high temperature. It is usually caused by a buildup of debris or limescale inside the main heat exchanger, which prevents heat from being transferred to your water and instead sends it out through the flue. In some cases, a faulty sensor or a damaged burner seal may also be sending incorrect readings to the control board.
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 7 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Could it be time for a new boiler?
If repair costs are adding up, a new energy-efficient boiler could be the smarter long-term choice.
Affiliate links — we may earn a commission at no extra cost to you.