The outdoor temperature sensor is out of normal operating range, meaning the sensor is either open or shorted for more than 3 seconds. The E39 code will flash and alternate with the DHW set point, ensuring the system continues to supply hot water.
- If the Outdoor Temperature Sensor returns to normal operating range, this error code will clear on its own. Normal operating range of the sensor is 40oF–122oF.
- Check the Outdoor Temperature Sensor. Ensure it is properly wired and connected, and that there are no breaks, cuts, or other visible issues with the sensor wire.
- Use an ohmmeter to check resistance on the outdoor temperature sensor.
- Replace Outdoor Temperature Sensor if it fails the resistance test.
