Worcester Bosch Greenstar 4000 Combi fault 363

System fault boiler electronics / basic controller

Gas boiler

What it means

Fault category V. System fault boiler electronics / basic controller.

Likely causes

  1. Faulty ionisation cable
  2. Faulty electrodes or cable
  3. Faulty control unit or burner control unit
  4. Misfiring ignition transformer
  5. Incorrect gas type
  6. Incorrect gas supply pressure
  7. Power supply issue
  8. Damaged or blocked flue system
  9. Incorrect gas/air ratio
  10. Faulty external gas flow monitor (natural gas)
  11. Faulty burner
  12. Faulty gas valve

Where to start

  1. Check and replace the ionisation cable
  2. Check and replace the electrodes if required
  3. Check the ignition transformer function for misfiring in the Function check menu, Ignition test

The full answer, free

  • 7 more checks in order
  • How to put it right, step by step
  • The manual page for this fault (page 75), right under the answer

Safety: Isolate gas and power before you open the case. If you have been into the gas side, do a tightness test, and a combustion and flue check before you hand back. Gas Safe (UK) or RGI (Ireland) work only.

From the Worcester Bosch manual for the Greenstar 4000 Combi. Check the model on the data plate before you order parts.

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