Boiler shuts down with E02, no flame proven after ignition attempt

Safety: Turn off power and close the gas shutoff valve before opening the combustion chamber.

• Step 1 – Inspect flame sensor: Remove the burner cover on the Triangle Tube boiler. Locate the flame sensor rod (often combined with the ignition electrode). Remove the mounting screw and gently pull out the rod. Clean the metal portion with fine steel wool or emery cloth until shiny, then wipe clean. Reinstall and tighten securely.
• Step 2 – Check grounding: Verify the boiler chassis ground wire is firmly attached to the cabinet and to the control board ground terminal. Tighten any loose screws. A poor ground can prevent the control from sensing flame.
• Step 3 – Examine burner and combustion area: Look for heavy soot, rust flakes, or debris on the burner head that could interfere with flame stability. Vacuum loose debris with a soft brush attachment (do not damage the burner mesh or ports).
• Step 4 – Reset and test: Restore gas and power, then reset the boiler. Observe ignition: if flame appears but E02 still occurs, the flame-sense signal may be weak.
• Call a professional: A licensed technician should measure microamp flame signal, verify gas pressure, and replace the flame sensor, burner, or control board if the signal remains out of spec.