How much does it cost to fix Vaillant error code D.118 (2)?

Typical repair cost for the Vaillant D.118 (2) fault is £180-350 including labour.

D.118 (2) High

Vaillant D.118 (2) Fault Code

Q: What does the Vaillant D.118 (2) fault code mean?

Your boiler has detected a communication failure with a safety monitoring sensor, which prevents it from operating to ensure your protection.

Also written as D1182 — same fault.

The Vaillant D.118 (2) fault code means: your boiler has detected a communication failure with a safety monitoring sensor, which prevents it from operating to ensure your protection.. It appears on 2 Vaillant models in our database.

Technical description: CO sensor fault number: Heater open circuit

Typical repair cost £180-350 (including labour)

Engineer required

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

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Vaillant models that show the D.118 (2) fault code

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

Source

Vaillant D.118 (2) fault code information on this page is sourced and cross-checked against the official Vaillant service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026