BoilerFaultCodesYour boiler’s internal computer brain is overheating, which has caused the system to shut down for safety.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Electronics temperature too high: Electronics too hot due to external effect, electronics defective
What causes this fault?
This fault occurs when the boiler's main control board reaches a temperature that risks melting internal components or causing a fire. The most common reasons are an internal electrical short circuit, poor ventilation around the boiler casing, or being located too close to an external heat source. If the heat is generated from within the board itself, it usually indicates that a specific electronic component has failed and is drawing too much current.
This fault is more common during heatwaves in the summer, especially if the boiler is installed in a poorly ventilated cupboard or a hot loft space.
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 F.65 — 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.