Medium
F.74 on Glow-worm Sustain 12s

Your boiler has detected that the internal water pressure is too high or the sensor that measures it is reading incorrectly.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

What the manual says

Manufacturer manual

Water pressure sensor signal in the wrong range (too high)

From this model's manual
Verified against the Glow Worm Sustain 12s installation & service manual, page 34.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

DIY fix possible

Check the pressure gauge on the front of the boiler or in the digital menuIf the pressure is above 2.5 bar, bleed a radiator using a radiator key to release some waterEnsure the blue filling loop handles under the boiler are fully tightened and not accidentally left open

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