Furnace locks out with code 2 shortly after ignition, burner shuts down

Safety first: Turn off power and gas before removing covers. Work on gas train and combustion components only if you are licensed.

User/installer checks:

• Ventilation and flue: Ensure the flue terminal is not blocked by debris, snow, or vegetation. Confirm that air inlets are unobstructed.
• Reset and observe: Reset the boiler and watch the sequence: ignition, flame established, then shutdown with code 2. Note any unusual noises or smells.

Technician checks:

• Check gas pressure stability: Measure inlet and burner pressure during operation. Look for pressure drops when other appliances run. Correct supply or regulator issues.
• Inspect and clean burner: Remove the Intergas premix burner. Clean off any debris, rust, or soot. Check burner gasket and replace if damaged.
• Test flame sensor: Clean the flame electrode with fine abrasive. Measure ionization current according to Intergas specifications. Replace electrode if readings are low.
• Check gas valve modulation: Using manufacturer procedures, verify that the gas valve receives correct modulation signal from the PCB and that the valve responds smoothly. Replace the gas valve if it fails tests.

If flame repeatedly drops out, do not continue to operate the appliance. Call an Intergas-authorized technician.