Low
F6 on Heatline Solaris

Your boiler is having trouble communicating with the outside temperature sensor, which helps it run efficiently based on the weather.

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

External sensor fault (where fitted)

From this model's manual
Verified against the Heatline Solaris Combi installation & service manual, page 21.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

DIY fix possible

Locate the external sensor on an outside wall to check for obvious physical damage or loose wiresTurn the boiler power off and back on to see if the fault clearsIf the issue persists, the boiler will still provide heat but will revert to standard internal settings

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