High Lockout
ERROR CODE 6 on Ideal Icos HE

Your boiler is having trouble measuring the temperature of your hot water, likely meaning you won't have any hot water available.

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

DHW THERMISTOR FAULT

What causes this fault?

This fault occurs when the sensor responsible for monitoring your hot water temperature has failed or is sending incorrect electrical signals back to the main control board. Over time, these sensors can degrade due to constant heat cycles or internal corrosion, leading the boiler to shut down for safety because it can no longer regulate water temperature correctly.

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

ERROR CODE 5View →ERROR CODE 1View →

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