this outdoor temperature sensor is the likely culprit

OEM Standards: Guaranteed to meet Trane factory specifications for fitment and electrical load handling

The AS-60993-03 measures approximately 8

The robust circuitry is designed to handle voltage fluctuations and harsh mechanical room environments

Lochinvar & A.O. Smith 100093811 Door Switch 319847-401 this outdoor temperature sensor isWhen you're troubleshooting a natural gas water heater that won't ignite or is throwing intermittent error codes, the Lochinvar & A. O. Smith 100093811 Door Switch is a critical safety component to inspect. Designed specifically for the NAT FG40T40 series, this OEM replacement door switch serves as a definitive safety interlock, ensuring the burner assembly is correctly isolated and the access door is fully secured before allowing the ignition