Boiler locks out with code 02, fan runs but no ignition, or ignition stops quickly

Safety first: Isolate power and gas before removing the boiler case. Only qualified personnel should access combustion components.

• Reset and observe: Reset the boiler and watch through the inspection window (if present). If the burner lights briefly then goes out, the flame signal may be weak.
• Check earth connections: Ensure the boiler has a solid earth connection at the spur and that the main earth wire inside the boiler is secure.
• Engineer tasks:
  • Remove and visually inspect the flame sensor electrode for cracks, heavy oxidation, or damage. Clean lightly with fine abrasive pad.
  • Check electrode gap and position relative to burner as per Vokera technical data.
  • Verify continuity of the flame sensor lead from electrode to PCB.
  • Measure flame rectification current with a suitable meter; compare with Vokera specifications.
  • If all else is correct, test/replace the main PCB.

Do not attempt to bend or reposition electrodes without the manufacturer’s data. Call a Gas Safe engineer if you are not fully competent.