Worcester Bosch Greenstar RI Heat Only fault 5
Ionisation detected after burner stopped / gas valve EV2 leak test failed / gas valve...
Gas boilerWhat it means
Locking fault covering multiple related conditions: ionisation detected after burner stopped, gas valve EV2 leak test failed, gas valve EV1 leak test failed, ionisation current detected before burner-start, gas valve error, or ionisation sensor shorted. Indicates gas valve leaking or false flame detected.
Likely causes
- Gas valve leaking
- False flame detected
- Ionisation sensor shorted
- Gas valve EV1 or EV2 leak test failure
Where to start
- Check gas valve for leaks
- Check ionisation sensor for short circuit
- Check ionisation current readings before burner start
The full answer, free
- How to put it right, step by step
- The manual page for this fault (page 53), 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 RI Heat Only. Check the model on the data plate before you order parts.