BoilerFaultCodesViessmann E4 Fault Code
The Viessmann E4 fault code means: your boiler has stopped working because it is not receiving the correct electrical power or an internal fuse has blown.. It appears on 8 Viessmann models in our database.
Technical description: Burner in fault position. Supply voltage 230 V fault. Check the supply voltage and the internal fuses.
What causes the Viessmann E4 fault?
This fault occurs when the boiler's main control board detects an issue with the incoming electrical supply or its own internal power distribution. It is typically triggered by a sudden power surge that blows a safety fuse or an underlying hardware failure within the electronic circuitry. Without a stable 230V connection, the boiler cannot safely power the ignition process or the fan, leading to a complete shutdown.
This fault is frequently seen following heavy summer storms, as lightning strikes or local power grid fluctuations can cause the electrical surges that blow internal fuses.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Viessmann models that show the E4 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Viessmann E4 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