How much does it cost to fix Viessmann error code EF?

Typical repair cost for the Viessmann EF fault is £150-£450 including labour.

EF High

Viessmann EF Fault Code

Q: What does the Viessmann EF fault code mean?

Your boiler is continuing to detect a flame even after it has been told to shut down, which is a safety precaution to prevent gas issues.

The Viessmann EF fault code means: your boiler is continuing to detect a flame even after it has been told to shut down, which is a safety precaution to prevent gas issues.. It appears on 1 Viessmann model in our database.

Technical description: Flame after a delay

What causes the Viessmann EF fault?

This fault occurs when the boiler's sensors detect heat or a flame signal even after the gas supply should have been cut off. The most common reason is a gas valve that is failing to close fully or a faulty electrode that is sending a false 'flame present' signal to the main control board.

Typical repair cost £150-£450 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Viessmann models that show the EF fault code

Click a model for the full fault code list and model-specific repair notes.

Vitodens Repair: £150-£450

Source

Viessmann EF 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