BoilerFaultCodesViessmann E5 Fault Code
The Viessmann E5 fault code means: your boiler has stopped working because it cannot confirm that a flame is burning safely, leading to a complete shutdown for your protection.. It appears on 9 Viessmann models in our database.
Technical description: Burner in fault position. Internal fault. Check the flame monitoring (ionisation electrode and lead).
What causes the Viessmann E5 fault?
This fault occurs when the boiler's control system cannot detect a steady flame after the ignition process has started. The most common reason is that the sensor responsible for 'seeing' the flame is either dirty, worn out, or damaged, causing the boiler to shut down as a safety precaution. In some cases, it can also be caused by an inconsistent gas supply or a failing electronic control board.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →Viessmann models that show the E5 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Viessmann E5 fault code information on this page is sourced and cross-checked against the official Viessmann service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026