BoilerFaultCodes.com
F6 Low Warning

Your boiler is having trouble communicating with the optional sensor that measures the temperature outside, which may cause your heating to behave unpredictably.

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.

Technical description: Outside Sensor Fault

What causes this fault?

This fault occurs when the boiler loses its electrical connection with the sensor mounted on the exterior of your home. The most common reasons are physical damage to the small sensor unit by the weather, or the thin communication wires becoming loose or corroded over time.

This fault often becomes apparent during the transition into autumn or winter when the boiler first attempts to use weather data to calculate your heating needs.

Typical repair cost £90-160 (including labour)

DIY fix possible

Check if any external wires leading to the sensor outside have been damaged or cut.Restart the boiler by turning the control knob to 'Reset' and then back to the desired setting.If the fault persists, contact a professional; the boiler will usually continue to provide heat using a default setting in the meantime.

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