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Worcester Bosch Greenstar 4000 Combi fault 234

Gas valve electrical fault

Gas boiler

What it means

Fault category V. Gas valve electrical fault.

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

Where to start

  1. Check the resistance on the gas valve (pins 1-2)
  2. Check the voltage to the gas valve when demand
  3. Check the gas supply to the property and the inlet on the gas valve (check drop on inlet)

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.

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