High Lockout
HJ-09 on Daikin D2CND

Your boiler has detected that the water pressure is too low to operate safely, causing it to shut down temporarily.

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

Low system pressure – increase the system pressure to 0.8 bar

What causes this fault?

This fault occurs because the internal sensors have detected that there is not enough water inside the central heating system to circulate safely. The most common reason is a minor leak in the pipework or radiators, though it can also happen if air was recently bled from your radiators without the pressure being topped up.

This issue is frequently seen at the start of autumn when homeowners turn their heating back on for the first time after the summer break.

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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