20 High

Dimplex 20 Fault Code

The Dimplex 20 fault code means: your boiler is failing to light a flame because the internal gas valve is not operating correctly, meaning your heating and hot water will not work.. It appears on 2 Dimplex models 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: No flame. Gas valve V1-V2 failure
Typical repair cost £250-£450 (including labour)

Engineer required

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

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Dimplex models that show the 20 fault code

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

Source

Dimplex 20 fault code information on this page is sourced and cross-checked against the official Dimplex service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026