High Lockout
D(1) on Potterton Flamingo RS40 RS50

Your boiler's internal temperature control sensor is failing or reporting incorrect information, preventing the system from heating up properly.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

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

Technical description

Thermostat out of calibration or faulty.

What causes this fault?

This fault occurs when the boiler's internal sensors can no longer accurately measure the temperature of the water inside the unit. The most common reason is that the mechanical thermostat or sensor has degraded over time, causing it to send incorrect signals or fail completely for safety reasons.

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

D(2)View →

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