Boiler displays E12; may occur during operation with strong wind or venting issues

Safety first: Turn off power and gas. Flue gases are hazardous; do not operate the boiler with venting disconnected.

• Inspect exterior vent terminations: Ensure intake and exhaust are clear of obstructions and meet Ruud clearance requirements from windows, doors, and grade.
• Check venting layout: Compare installed vent length and number of elbows to the Ruud installation manual. Excessive length or improper pipe size can cause E12.
• Examine flue sensor: Locate the flue gas temperature sensor on the exhaust side. Inspect wiring and connections. Replace the sensor if damaged.
• Wind effects: If E12 occurs only during high winds, a vent termination kit or relocation may be required. This should be evaluated by a qualified installer.