BoilerFaultCodesAtag 108 Fault Code
The Atag 108 fault code means: your boiler has temporarily stopped working because the water pressure inside the system has dropped too low.. It appears on 18 Atag models in our database.
Technical description: Pressure < Pmin (< 0.5 bar), Filling needed
DIY fix possible
Locate the filling loop or key underneath your boiler.Open the valves slowly to let mains water into the heating system.Watch the pressure gauge on the front of the boiler until the needle reaches between 1.0 and 1.5 bar, then close the valves tightly.
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Atag models that show the 108 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Atag 108 fault code information on this page is sourced and cross-checked against the official Atag service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 31 August 2026