Burner locks out shortly after start attempt, red lockout light on burner control, furnace does not ignite

Safety first: Turn off power to the furnace at the service switch and shut off the oil supply valve before opening any burner compartment. Allow hot surfaces to cool.

Step-by-step checks:

• Reset only once: Press the burner reset button only one time. If the burner locks out again, do not keep resetting—this can flood the combustion chamber with oil.
• Verify oil supply: Ensure the oil tank has fuel. Open the oil shutoff valve fully. Check the flexible oil line to the Riello pump for kinks or visible leaks.
• Bleed the oil pump: Place a container under the Riello fuel pump bleed port. Loosen the bleed screw slightly, restore power, and call for heat. Let oil flow until it is free of air bubbles, then tighten the screw and shut power back off.
• Inspect ignition components: Remove the burner cover. Check the ignition transformer/ignition coil connections. Inspect ignition electrodes for cracks, carbon buildup, or incorrect gap. Clean with fine emery cloth and set to the Riello-specified gap and position relative to the nozzle.
• Check nozzle and combustion head: Remove the oil nozzle and inspect for clogging or deformation. Replace with the exact Riello-specified size and spray pattern. Clean the combustion head and air tube of soot and debris.
• Check flame sensor (photocell): Gently remove the photocell from its holder. Clean the lens with a soft cloth. Reinstall firmly, ensuring it has a clear view of the flame area.

If the burner still locks out on A01 after these steps, the control box or ignition transformer may be faulty. Contact a qualified Riello technician for further diagnosis and combustion setup.