Heater displays E05 and will not fire; often occurs in windy or confined installations

Safety: Turn off power and gas. Exhaust gases are hazardous; ensure good ventilation while working.

• Inspect exhaust outlet: Check the Sta-Rite heater flue outlet for obstructions such as leaves, nests, or debris. Remove any blockage.
• Check vent termination: For indoor or vented models, verify that the vent pipe is properly sized, not crushed, and terminates according to Sta-Rite installation guidelines. Correct any obvious venting issues.
• Examine flue sensor: Locate the flue temperature sensor (often mounted on the exhaust collector). Inspect wiring and connector. With power off, test sensor resistance and compare to Sta-Rite specifications; replace if out of range.
• Look for soot buildup: Remove burner access and inspect the heat exchanger surfaces for heavy soot, which indicates poor combustion and high flue temperatures. Sooted exchangers should be cleaned by a qualified technician.
• Replace flue sensor if needed: If the sensor is open, shorted, or reading incorrectly, install a new Sta-Rite flue temperature sensor.