High Lockout
F22 on Vaillant ecoTEC Plus 836

Your boiler has stopped working because the water pressure is too low for it to operate safely.

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

Fault F22 will be stored in the fault list if the water pressure falls below 0.03 MPa (0.3 bar).

What causes this fault?

This fault occurs when the water level inside your central heating system drops too low for the boiler to function safely. The most common reason is a slow leak from a radiator valve or a pipe joint, but it can also happen if you have recently bled your radiators without topping the water back up.

This fault is frequent in autumn when homeowners turn their heating back on for the first time and discover pressure has dropped over the summer months.

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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