BoilerFaultCodesYour boiler is failing to communicate properly with the equipment used to heat your hot water tank, meaning you may lose hot water.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Without auxiliary function for DHW loading
What causes this fault?
This fault occurs when the boiler's main control board loses its electronic connection with the components responsible for heating your hot water cylinder. The most common reason is a breakdown in the communication module or a faulty sensor that prevents the boiler from knowing the water temperature in the tank. Without this data link, the boiler stops heating the cylinder as a safety precaution.
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 63:0 — 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.