High
21 on Saunier Duval Isofast F28E

Your boiler has switched itself off because the system water pressure has dropped too low to operate safely.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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

Water pressure too low: open the blue tap (t) situated under the boiler until a pressure of 1.5 bar is obtained.

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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