How much does it cost to fix Vaillant error code Er.3?

Typical repair cost for the Vaillant Er.3 fault is £180-350 including labour.

Er.3 High

Vaillant Er.3 Fault Code

Q: What does the Vaillant Er.3 fault code mean?

Your boiler has detected an issue with the internal ventilation system that removes exhaust gases, so it has automatically stopped working to keep your home safe.

Also written as ER3 — same fault.

The Vaillant Er.3 fault code means: your boiler has detected an issue with the internal ventilation system that removes exhaust gases, so it has automatically stopped working to keep your home safe.. It appears on 2 Vaillant models in our database.

Technical description: Fan

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 Er.3 fault code

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

Thermocompact Repair: £180-350
Turbomax Pro 28 2E Repair: £180-350

Source

Vaillant Er.3 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