Low
F39 on Ferroli Optimax HE 31 C

Your boiler is struggling to detect the temperature outside, so it is defaulting to its standard internal settings to keep your home warm.

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 probe fault (Sensor damaged or short-circuited)

From this model's manual
Verified against the Ferroli/Ferroli Optimax He 31 C 4726742 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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Related fault codes

F37View →F40View →

All 32 fault codes on the Optimax HE 31 C

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

A01A02A03A04A05A06A41F04F05F07F10F11F12F13F14F15F20F21F24F34F35F37F40F41F42F43F47F50F51Low system pressureNo burner ignition

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