What does the Johnson Starley OVERHEAT LOCKOUT fault code mean?

Your boiler has shut itself down because it is getting too hot inside, usually because water is not flowing through your heating system properly.

How much does it cost to fix Johnson Starley error code OVERHEAT LOCKOUT?

Typical repair cost for the Johnson Starley OVERHEAT LOCKOUT fault is £120-250 including labour.

Manufacturer manual

Flow/Return differential in excess of 30°C or circulation issues

Shared across the Quantec range

This code is shared by the boilers in this range, which use the same control board. It may not be printed in this exact variant’s manual.

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

Boiler cover options

A cover plan would handle faults like OVERHEAT LOCKOUT: no call-out fees, no surprise bills.

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Seeing a different code? Every code this model can display, in one place.

Each noise points to a different fault.

On a combi it is usually the diverter valve. On a system boiler, the motorised valve.

1 to 1.5 bar when cold on most UK boilers, from the manuals.