F (Low system water pressure) High

Saunier Duval F (Low system water pressure) Fault Code

Q: What does the Saunier Duval F (Low system water pressure) fault code mean?

Your boiler has stopped working because the water pressure inside the heating system has dropped too low to operate safely.

Q: How much does it cost to fix Saunier Duval error code F (Low system water pressure)?

Typical repair cost for the Saunier Duval F (Low system water pressure) fault is £0-80 including labour.

Also written as FLOWSYSTEMWATERPRESSURE — same fault.

The Saunier Duval F (Low system water pressure) fault code means: your boiler has stopped working because the water pressure inside the heating system has dropped too low to operate safely.. It appears on 1 Saunier Duval model in our database.

Technical description: The green running light will change to a red flashing light and the display will flash the letter ‘F’ with the low system water pressure fault and the current system pressure.

Typical repair cost £0-80 (including labour)

DIY fix possible

Locate the external filling loop, usually situated underneath the boiler casing.Open the filling valve(s) slowly to allow mains water into the system.Keep watching the pressure gauge until it reaches between 1.0 and 1.5 bar, then firmly close the valve(s).

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Saunier Duval models that show the F (Low system water pressure) fault code

Click a model for the full fault code list and model-specific repair notes.

Thema F 30 E Plus Repair: £0-80

Source

Saunier Duval F (Low system water pressure) fault code information on this page is sourced and cross-checked against the official Saunier Duval service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026