BoilerFaultCodes.com
61 High Lockout

Your boiler's internal temperature sensors are struggling to read the water temperature correctly, preventing the system from heating up properly.

Call an engineer soon

Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: Sensor fault

What causes this fault?

This fault occurs when the boiler's internal thermometers, known as NTC sensors, stop communicating accurate temperature data to the main control board. The most common reason is that the sensors have physically degraded over time or have become coated in internal system debris, meaning they can no longer tell the boiler if the water is hot or cold. As a safety precaution, the boiler stops firing because it cannot be sure it won't overheat.

This fault can be more noticeable in winter when the boiler is under high demand and internal components are expanding and contracting more frequently due to the heat.

Typical repair cost £90-160 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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