How much does it cost to fix Vaillant error code d.33?

Typical repair cost for the Vaillant d.33 fault is £0-120 including labour.

d.33 Low

Vaillant d.33 Fault Code

Q: What does the Vaillant d.33 fault code mean?

Your boiler is displaying the real-time speed of the internal fan as part of its normal diagnostic checks, which is usually just an information code rather than a breakdown.

Also written as D33 — same fault.

The Vaillant d.33 fault code means: your boiler is displaying the real-time speed of the internal fan as part of its normal diagnostic checks, which is usually just an information code rather than a breakdown.. It appears on 25 Vaillant models in our database.

Technical description: Fan speed target value: Current value in rpm. Fan speed=Display value x 100

Typical repair cost £0-120 (including labour)

DIY fix possible

No action required; this is an information code.Observe the display to confirm it clears once the check is complete.Restart the boiler if the code remains frozen for a long period.

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Vaillant models that show the d.33 fault code

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

Source

Vaillant d.33 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 31 August 2026