BoilerFaultCodesYour boiler's main control board has detected an internal communication error, meaning it cannot process commands correctly.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: –
What causes this fault?
This fault occurs when the boiler's central brain, the main control board, experiences an internal electronics failure or loses the ability to talk to its sensors. The most common reason is a hardware malfunction within the PCB itself or a loose connection in the internal wiring harness that prevents data from flowing correctly.
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 F66 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Ferroli Bluehelix Tech 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.