High Lockout
F.28 on Vaillant ecoTEC

Your boiler is not receiving gas or is unable to light a flame to provide heating and hot water.

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

Appliance does not start: Attempts to ignite during start failed

What causes this fault?

This fault occurs when the boiler tries to light itself several times but fails to detect a flame, causing the system to shut down for safety. The most common reasons include a lack of gas reaching the unit, a blocked burner, or a component failure in the ignition system that prevents the initial spark. It can also be triggered by external issues like a shut-off gas meter or a temporary interruption in your local gas supply.

In freezing temperatures, this fault can be caused by a frozen gas meter regulator or a blocked condensate pipe, both of which prevent the boiler from completing its ignition cycle.

Engineer required

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

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