Weil McLain 381-356-589 Temperature Sensor

The Weil McLain 381-356-589 Supply Temperature Sensor is a threaded probe sensor with a blue connector. Weil McLain's CGa Series 4 and CGi Series 5 parts lists name 381-356-589 the Temperature/LWCO sensor, and it appears on the section assembly pages of both lists, so it is a manufacturer-listed part for those boiler lines. Parts retailers describe the same number as a supply temperature sensor.

A probe sensor like this reads the temperature of the water in the boiler and passes that reading to the control. The LWCO in the manufacturer's name stands for low water cutoff, a safeguard that stops the burner when there is not enough water in the boiler. Because the sensor is a protective and control input, a failed or drifting unit can cause erratic temperature readings, nuisance lockouts or error codes on the display. Replacing it with the listed part gets the control back to reading the real temperature.

The sensor installs with its threaded body into the boiler and plugs into the harness with the blue connector. Take the usual precautions when removing the old one: make sure the boiler is cool and the pressure is relieved, then follow the boiler manual for sealing the threads and handling the connector. Check the old sensor against the product photo before you order, and send us your boiler model and serial number if you would like our team to confirm fit before you buy.

Key Benefits

• Listed for CGa Series 4 and CGi Series 5: 381-356-589 appears in both Weil McLain parts lists as the Temperature/LWCO sensor.
• Threaded Probe Design: The threaded body threads into the boiler so it reads water temperature directly.
• Blue Connector: Plugs into the harness with a connector that is easy to recognize against the old sensor.
• Control Input Replacement: Restores accurate temperature readings when a failing sensor is causing erratic behavior or lockouts.

Common Questions

• Is the 381-356-589 a supply temperature sensor or an LWCO sensor? Weil McLain's parts lists name it the Temperature/LWCO sensor, and retailers describe the same number as a supply temperature sensor. It is one part.
• Which boilers list the 381-356-589? Weil McLain's CGa Series 4 and CGi Series 5 parts lists both show it. Send us your model and serial number and our team will confirm fit before you buy.
• What does a failing sensor look like? Typical signs are erratic temperature readings, nuisance lockouts and sensor error codes on the control.

Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.