High
Overheat Lockout on Keston Heat 45

Your boiler has detected that it is running too hot and has automatically turned itself off to prevent damage.

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.

What the manual says

Manufacturer manual

Fill System to 1 Bar, Vent System, Check Pump Spins Free, Reset Boiler

From this model's manual
Verified against the Keston/Keston Heat 45 installation & service manual, page 53.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

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

E04View →E05View →

All 36 fault codes on the Heat 45

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

16747576787980818283848586878990BCC FaultCylinder Thermistor FaultE18Error 20False Flame LockoutFan FaultFlame LossFlow Thermistor FaultFlow/Flue Thermistor FaultFlow/Return ReversedFlue Thermistor FaultIgnition LockoutL5Low Mains VoltageLow Water PressureOutside Sensor FaultPCB FaultReturn Thmr FaultToo Many Resets

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