BoilerFaultCodesYour boiler has sensed a dangerous level of overheating within its internal system and has locked itself down as a safety precaution.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Heat exchanger thermal fuse tripped
What causes this fault?
This fault occurs when the boiler's internal temperature reaches a critically high level, causing a safety fuse to blow and permanently cut the power to prevent a fire or explosion. It is usually caused by a severe lack of water circulation, a major blockage in the heat exchanger, or a complete failure of the internal pump. Unlike a standard overheat, this fuse is a one-time safety component that cannot be reset electronically.
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 E13 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Baxi Avanta is discontinued — time for a new one?
Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
Affiliate links — we may earn a commission at no extra cost to you.