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Worcester Bosch Greenstar 4000 Combi fault 238

Boiler electronics faulty

Gas boiler

What it means

Fault category V. Boiler electronics faulty.

Likely causes

  1. Gas supply issue
  2. Loose connections on gas valve or board
  3. Harness continuity fault
  4. Water on gas valve connections
  5. Incorrect gas valve resistance
  6. Incorrect gas type
  7. Incorrect gas supply pressure
  8. Damaged or blocked flue system
  9. Incorrect gas/air ratio
  10. Faulty gas valve
  11. Misfiring ignition transformer
  12. Power supply issue
  13. Faulty electrodes or cable
  14. Faulty external gas flow monitor (natural gas)
  15. Faulty burner
  16. Faulty seals around the burner
  17. Faulty internal flue seals
  18. Faulty case seals
  19. Combustion fault
  20. Restricted gas supply
  21. Livestock stables or storage rooms for fertilisers near appliance
  22. Permanent ammoniac concentration in installation area

Where to start

  1. Check the gas supply to the property and the inlet on the gas valve (check drop on inlet)
  2. Check the connections on the gas valve and the board (loose connection)
  3. Check the continuity down harness and replace if required

The full answer, free

  • 53 more checks in order
  • The readings and component tests from the manual
  • How to put it right, step by step
  • The manual page for this fault (page 73), right under the answer
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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.

Other Worcester Bosch Greenstar 4000 Combi fault codes