Low
Outside Sensor Fault on Keston Heat 55

Your boiler's outdoor weather sensor is failing to communicate properly, meaning it cannot automatically adjust your heating based on the outside temperature.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

What the manual says

Manufacturer manual

Check Outside Sensor Wiring, Check Outside Sensor (10K @ 25°C, 2K at 66°C)

From this model's manual
Verified against the Keston/Keston Heat 45 installation & service manual.
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 fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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All 36 fault codes on the Heat 55

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

167475767778798081828384858687888990BCC FaultCylinder Thermistor FaultError 20Ext’ Interlock OffFalse Flame LockoutFan FaultFlame LossFlow/Flue Thermistor FaultFlow/Return ReversedFlue Thermistor FaultIgnition LockoutLow Mains VoltageLow Water PressureOverheat LockoutPCB FaultReturn Thmr FaultToo Many Resets

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