Furnace locks out shortly after ignition attempt, display shows 02, burner lights briefly then goes out

Safety warning: Work on gas and combustion components must be done with power and gas off. Only qualified personnel should perform live gas pressure or combustion tests.

Basic user checks:

• 1. Reset the unit: Use the reset button on the Immergas control panel. Observe whether the burner lights and how long it stays on before 02 appears.
• 2. Check for drafts or flue issues: Strong wind or a partially blocked flue can destabilize the flame. Inspect the flue terminal outside for obstructions (ice, nests, debris) and ensure the terminal is not covered.
• 3. Verify gas supply stability: If other gas appliances fluctuate or go out, contact your gas supplier to check supply pressure.

Technical checks (technician):

• Inspect and clean the ionization electrode and burner surface; ensure good metal-to-metal contact for grounding.
• Check ionization current with a meter according to Immergas specifications; replace electrode if current is low.
• Verify gas valve pressure settings and adjust only with a calibrated manometer and combustion analyzer.
• Check wiring between ionization electrode and main PCB; replace PCB if flame signal circuit is defective.