Remedy
Tip: Check the ceramic insulator is not damaged, this can cause the spark to earth, twist and pull the ceramic insulator to ensure it is not broken.
1. Check the flame sense and the lead and replace if required.
2. Check the earth tags on the boiler and on the electrodes.
3. Check the operation of the siphon and no water collecting in the sump.
4. Replace the air and/or gas ratio control valve.
5. Replace the control unit and/or burner control unit.