BoilerFaultCodesVokera d1 Fault Code
Also written as D1 — same fault.
The Vokera d1 fault code means: your boiler has stopped working because the waste water pipe is blocked, likely by debris or ice if it is cold outside.. It appears on 4 Vokera models in our database.
Technical description: Appears if the condense trap/pipe has become blocked.
What causes the Vokera d1 fault?
This fault occurs when the boiler detects that waste water, known as condensate, cannot flow away through the drainage pipe. The most common cause is a physical blockage in the internal trap or the external pipework, which triggers a safety sensor to prevent water from backing up into the boiler's combustion chamber. If the water cannot escape, the boiler will shut down immediately to protect its internal electrical components from water damage.
This fault is extremely common during freezing winter temperatures, as the external portion of the condensate pipe can freeze over and become completely blocked with ice.
DIY fix possible
Locate the plastic pipe leading from the boiler to your outside drain.If it is freezing weather, pour warm (not boiling) water over the external pipe to melt any ice blockages.If it is not freezing, check the internal condensate trap for debris and clear it if accessible.Reset the boiler using the control dial or button.
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Gas Safe Register →Vokera models that show the d1 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Vokera d1 fault code information on this page is sourced and cross-checked against the official Vokera service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026