BoilerFaultCodesWhat the manual says
Manufacturer manualpump pre-run
From this model's manual
Verified against the Glow Worm/Glow Worm Flexicom Cx installation & service manual, page 45.
What causes this fault?
This isn't actually a fault, but rather a brief status message where the boiler circulates water internally before firing the burner. It ensures that any trapped heat is cleared and proper flow is established to protect the heat exchanger from overheating. Once this short preparation phase is complete, your heating or hot water will begin as normal.
DIY fix possible
This fault may be fixable without an engineer. Check your manual first.
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Related fault codes
All 47 fault codes on the Flexicom cx
Seeing a different code? Every code this model can display, in one place.