How much does it cost to fix Vaillant error code d.37?

Typical repair cost for the Vaillant d.37 fault is £180-350 including labour.

d.37 High

Vaillant d.37 Fault Code

Q: What does the Vaillant d.37 fault code mean?

Your boiler is having difficulty communicating correctly with its internal gas control system, which prevents it from firing up safely.

Also written as D37 — same fault.

The Vaillant d.37 fault code means: your boiler is having difficulty communicating correctly with its internal gas control system, which prevents it from firing up safely.. It appears on 2 Vaillant models in our database.

Technical description: Modulator current

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.37 fault code

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

aquaPLUS Repair: £180-£350
ecoTEC plus Aquaplus Repair: £180-350

Source

Vaillant d.37 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