How much does it cost to fix Baxi error code E.04 – .00?

Typical repair cost for the Baxi E.04 – .00 fault is £180-£350 including labour.

E.04 – .00 High

Baxi E.04 – .00 Fault Code

Q: What does the Baxi E.04 – .00 fault code mean?

Your boiler has lost communication with the internal gas control system, meaning it cannot safely release fuel to create a flame.

Also written as E0400 — same fault.

The Baxi E.04 – .00 fault code means: your boiler has lost communication with the internal gas control system, meaning it cannot safely release fuel to create a flame.. It appears on 24 Baxi models in our database.

Technical description: Gas valve error – gas valve not detected.

What causes the Baxi E.04 – .00 fault?

This fault occurs when the boiler's central brain loses its electronic connection with the gas valve, which is the component responsible for letting fuel into the burner. The most common reason is a loose or damaged wiring connection between these two parts, or an internal electronic failure within the gas valve itself.

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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Baxi models that show the E.04 – .00 fault code

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

Source

Baxi E.04 – .00 fault code information on this page is sourced and cross-checked against the official Baxi service / installation manuals for each affected model.

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