BoilerFaultCodesYour boiler has lost connection to its outdoor thermometer because the wiring has developed a fault or been damaged.
This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.
Technical description: Shortcut outside sensor
What causes this fault?
This fault occurs when the electrical connection to your outdoor temperature sensor is interrupted by a short circuit. The most common reasons are water getting into the sensor housing or the external wiring being accidentally damaged or pinched against the wall.
This issue is more frequent during periods of heavy rain or driving wind, which can force moisture into electrical connections that aren't perfectly sealed.
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 27 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.