BoilerFaultCodesSaunier Duval 0.5bar Fault Code
Also written as 05BAR — same fault.
The Saunier Duval 0.5bar fault code means: your boiler has lost pressure, which means there isn't enough water inside the system to circulate heat throughout your home.. It appears on 5 Saunier Duval models in our database.
Technical description: Lack of water fault (<0.5b)
DIY fix possible
Locate the filling loop, which is usually a flexible silver hose with one or two valves underneath your boiler.Open the valves slowly to allow mains water into the system while watching the pressure gauge on the front of your boiler.Close the valves firmly once the needle on the gauge reaches between 1.0 and 1.5 bar.
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Saunier Duval models that show the 0.5bar fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Saunier Duval 0.5bar fault code information on this page is sourced and cross-checked against the official Saunier Duval service / installation manuals for each affected model.
- Saunier Duval Themaclassic F35E manual (PDF)
- Saunier Duval Thema F 30 E Plus manual (PDF)
- Saunier Duval Themaclassic Plus F30E manual (PDF)
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 31 August 2026