BoilerFaultCodesViessmann EL Fault Code
The Viessmann EL fault code means: your boiler is currently running an automatic air-purging program to remove air bubbles from the system and does not require a repair.. It appears on 5 Viessmann models in our database.
Technical description: Whilst venting is in progress (constant temperature control unit)
What causes the Viessmann EL fault?
This code appears when the boiler detects air pockets within its internal heat exchanger or the wider pipework. It physically triggers an automated venting sequence to push these bubbles out of the system, which helps prevent noisy operation and ensures efficient heat transfer. This usually happens after the system has been drained, refilled, or when new water has been added to the radiators.
This is most common in autumn when homeowners bleed their radiators or top up the system pressure in preparation for the heating season.
DIY fix possible
Wait approximately 20 minutes for the automated venting process to completeCheck that the system water pressure is between 1.0 and 1.5 barThe code should disappear and be replaced by the normal temperature display once finished
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Gas Safe Register →Viessmann models that show the EL fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Viessmann EL 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