BoilerFaultCodesVokera 91 Fault Code
The Vokera 91 fault code means: your boiler has detected a temporary service issue that is preventing it from completing its ignition sequence, though it may resolve itself or require a simple reset.. It appears on 3 Vokera models in our database.
Technical description: Temporary fault code (Refer to section 7.10)
What causes the Vokera 91 fault?
This fault occurs when the boiler's internal computer detects a temporary electronic glitch or a weak signal during the ignition process. It is often caused by the flame sensing electrode failing to confirm that the gas has lit correctly, or a brief dip in the communication between internal control components.
DIY fix possible
Locate the mode selector switch on the front panelTurn the dial to the 'OFF/RESET' position and wait for 5 secondsTurn the dial back to the original winter or summer position to see if the error clears
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Gas Safe Register →Vokera models that show the 91 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Vokera 91 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