Warmflow B-series and Bluebird Fault codes & diagnostics

1 fault code with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.

Heat Only Oil 1990-2015 Discontinued
Download the Warmflow B-series and Bluebird manual The official installation & service manual (PDF) — the exact document these fault codes were verified against. PDF

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Fault codes

All 1 documented codes

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Burner control box lockout light lit

Your boiler's burner has stopped running for safety reasons, which usually means it tried to fire up but couldn't detect a flame.

High DIY-safe £100-250

What to check first

  1. Check that you have enough oil in your storage tank
  2. Ensure the oil supply valve is fully open
  3. Press the illuminated reset button on the burner control box once
  4. If the boiler fires and then cuts out again, do not continue resetting and call a technician

Parts commonly replaced

  • Fuel nozzle
  • Oil pump filter
  • Photocell
  • Ignition electrodes

Related codes

Full explanation for Burner control box lockout light lit
Status & diagnostic codes

3 operating states & engineer diagnostics

Not faults — these are normal operating states. Tap to expand.

3306 Diagnostic This code is simply a technical reference for your boiler's manual version and does not indicate an actual mechanical fault. CD10 Diagnostic Your boiler is flagging a technical requirement regarding its installation records, which means it needs a certified professional to confirm the setup meets current safety regulations. CD11 Diagnostic Your boiler is displaying a code indicating that the mandatory safety and performance paperwork required after its initial installation or servicing has not been properly registered or finalised.