High
Red neon on fascia illuminated on Glow-worm Fuelsaver Complheat 40 55

Your boiler has stopped working because the water level inside your heating system 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.

What the manual says

Manufacturer manual

Low water pressure; fill central heating system, pressure 0.7bar min.

From this model's manual
Verified against the Fuelsaver Complheat 65 80 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 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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