54:2 Low

Viessmann 54:2 Fault Code

Also written as 542 — same fault.

The Viessmann 54:2 fault code means: your boiler is having trouble communicating with your solar heating control system, meaning your solar panels may not be providing hot water as intended.. It appears on 5 Viessmann models in our database.

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

Technical description: With Vitosolic 200 (automatical adjustment on recognition)

What causes the Viessmann 54:2 fault?

This fault occurs when the boiler's main control unit tries to automatically detect and link up with your solar thermal heating system but fails to receive a response. The most common reasons are a loose connection in the communication wiring, a blown fuse in the solar module, or a malfunction within the Vitosolic control box itself.

Typical repair cost £90-180 (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 54:2 fault code

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

Source

Viessmann 54:2 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