BoilerFaultCodesBuderus 8Y Fault Code
The Buderus 8Y fault code means: your boiler has paused because a safety switch related to your underfloor heating has detected a problem or has been disconnected.. It appears on 1 Buderus model in our database.
Technical description: External switch contact for underfloor heating system is open, the boiler will shut down.
DIY fix possible
Check if your underfloor heating thermostat is turned down too low or is turned off.Verify that the underfloor heating pump and manifold wiring centers have power.Ensure any manual safety limit thermostats on the underfloor pipework haven't been tripped by high temperatures.
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Buderus models that show the 8Y fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Buderus 8Y fault code information on this page is sourced and cross-checked against the official Buderus service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026