BoilerFaultCodesWhat the manual says
Manufacturer manualProduct in waiting period/operation block function due to low water pressure (flow/return spread too large)
From this model's manual
Verified against the Glow Worm Sustain 12s installation & service manual, page 33.
DIY fix possible
Check your boiler's pressure gauge and ensure it is between 1 and 1.5 bar.If the pressure is low, use the external filling loop to top it up to the correct level.Check all radiators are turned on and that the valves are not closed, which may be restricting water flow.
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