455 High

Viessmann 455 Fault Code

The Viessmann 455 fault code means: the boiler's internal computer has crashed or encountered a software glitch that is preventing it from managing its functions safely.. It appears on 1 Viessmann model 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: Error in program run monitoring
Typical repair cost £180-450 (including labour)

DIY fix possible

Turn the boiler power off at the fused spur switchWait for 60 secondsTurn the power back on and press the 'Reset' button on the display panel

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Viessmann models that show the 455 fault code

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

Source

Viessmann 455 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 7 July 2026