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

Typical repair cost for the Viessmann dE fault is £100-£190 including labour.

dE Medium

Viessmann dE Fault Code

Q: What does the Viessmann dE fault code mean?

Your boiler has lost connection with the temperature sensor that controls your second heating zone, meaning it cannot properly regulate the temperature for that part of your home.

Also written as DE — same fault.

The Viessmann dE fault code means: your boiler has lost connection with the temperature sensor that controls your second heating zone, meaning it cannot properly regulate the temperature for that part of your home.. It appears on 7 Viessmann models in our database.

Technical description: Heating circuit M2 room temperature sensor lead break

What causes the Viessmann dE fault?

This fault occurs when the boiler's control system can no longer detect a signal from the temperature sensor assigned to your second heating zone. It is usually caused by a loose electrical connection, a break in the thin sensor wiring, or the internal component of the sensor failing due to age.

Typical repair cost £100-£190 (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 dE fault code

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

Source

Viessmann dE 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