BoilerFaultCodesYour boiler has lost connection to the hot water cylinder sensor, meaning it cannot tell how hot your water is or when to heat it.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Short circuit in tank sensor | Cause: NTC defective, earth leak/short circuit in cable loom, damp plug connection
What causes this fault?
This fault occurs when the electrical signal from the hot water tank sensor is interrupted or fails to reach the boiler's control board. The most common reason is a physical breakage in the sensor’s internal wiring or moisture getting into the electrical plug, which confuses the boiler and prevents it from heating your water.
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.
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A boiler cover plan would cover faults like F.13 — no call-out fees, no surprises.
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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.
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