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Worcester Bosch Greenstar 4000 Combi fault 2950

No flame signal following starting procedure

Gas boiler

What it means

No flame signal detected following the starting procedure; burner restarts automatically after purging.

Likely causes

  1. Incorrect gas pressure
  2. Incorrect CO2 settings
  3. Faulty burner/heat exchanger gaskets
  4. Misfiring ignition transformer
  5. Incorrect gas type
  6. Incorrect gas supply pressure
  7. Power supply issue
  8. Faulty electrodes or cable
  9. Damaged or blocked flue system
  10. Incorrect gas/air ratio
  11. Faulty external gas flow monitor (natural gas)
  12. Faulty gas valve
  13. Faulty non-return valve in burner hood assembly
  14. Faulty seals around the burner
  15. Faulty internal flue seals
  16. Faulty case seals
  17. Flue system integrity problem
  18. Combustion circuit problem
  19. Combustion fault
  20. Cleaners containing chlorine or hydrogen halide (spray cans, primers, cleaners, paint, glue) stored or used near the appliance
  21. Build-up of dust

Where to start

  1. Check gas pressure whilst burning at full load
  2. Check CO2 settings, adjust if necessary
  3. Check burner and heat exchanger gaskets

The full answer, free

  • 57 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 77), 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