OVERHEAT THERMOSTAT High

Halstead OVERHEAT THERMOSTAT Fault Code

Also written as OVERHEATTHERMOSTAT — same fault.

The Halstead OVERHEAT THERMOSTAT fault code means: your boiler has detected that it is getting too hot and has automatically switched itself off to prevent any damage or safety issues.. It appears on 2 Halstead models in our database.

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: The appliance is fitted with an overheat thermostat. If the boiler overheats, the 'lockout' (red LED) will illuminate. This requires manual resetting of the thermostat button located behind the front casing.
Typical repair cost £120-250 (including labour)

Engineer required

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

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Halstead models that show the OVERHEAT THERMOSTAT fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Halstead OVERHEAT THERMOSTAT fault code information on this page is sourced and cross-checked against the official Halstead service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026