Fd High

Viessmann Fd Fault Code

Also written as FD — same fault.

The Viessmann Fd fault code means: your boiler's internal computer has crashed due to an ignition failure or electrical interference, preventing it from starting the burner.. It appears on 9 Viessmann models in our database.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: Burner blocked. Burner control unit fault. Check the ignition electrodes and leads. Check whether a strong interference (EMC) field exists near the equipment. If the fault is not removed, replace the control unit.

What causes the Viessmann Fd fault?

This fault occurs when the boiler's internal computer experiences a critical communication error or fails to verify the ignition process. The most common reasons are worn-out spark electrodes that can no longer light the gas, or electrical 'noise' from nearby appliances interfering with the boiler's sensitive electronics.

Typical repair cost £120-£450 (including labour)

DIY fix possible

Press the reset button or turn the boiler off and back on at the fused spur switchEnsure large electronic devices or powerful wireless routers are not sitting directly next to the boilerCheck if other gas appliances in your home are working to ensure gas is reaching the property

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Viessmann models that show the Fd fault code

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

Source

Viessmann Fd 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