Emergency
Er.4 on Vaillant Turbomax Pro 28 2E

Your boiler is failing to ignite because it cannot receive the gas supply required to produce a flame.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Act immediately

Turn off your boiler and stop using gas appliances. Call a Gas Safe engineer now. This fault can be dangerous if ignored.

What the manual says

Manufacturer manual

Gas valve (LPG or Natural gas)

From this model's manual
Verified against the Vaillant Turbomax Pro 28 2e installation & service manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

Engineer required

This is a emergency severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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