BoilerFaultCodesAtag 117 Fault Code
The Atag 117 fault code means: your boiler has detected that the water pressure inside the system is far too high, causing it to shut down for safety.. It appears on 7 Atag models in our database.
Technical description: Pressure greater than 3 bar or pump pressure increase is too high
What causes the Atag 117 fault?
This fault occurs when there is too much water forced into your heating system, often because the filling loop valves have been left slightly open or have developed a leak. It can also be caused by a failure in the expansion vessel, which is the internal part responsible for managing the natural pressure changes that happen when water gets hot.
This issue often surfaces when the heating is first turned on for autumn, as the heat causes the water to expand and pushes an already overfilled system past its safety limit.
DIY fix possible
Check that the internal or external filling loop valves are tightly closed.Bleed water from a radiator using a bleed key to reduce the system pressure.Monitor the pressure gauge until it returns to between 1.0 and 1.5 bar.Press the reset button to restart the boiler.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Atag models that show the 117 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Atag 117 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 27 April 2026