External sensor not communicating after replacement

Symptom

After replacing a faulty external sensor (temperature + humidity, CO2, or other EXT sensor), the new sensor still doesn’t communicate with the IO module. The sensor shows no values or remains in an error state.

Cause

There are three common causes:

1. Module cache - The IO module remembers the old sensor and doesn’t automatically detect the new one
2. Power cycle needed - The module needs a restart to reinitialize the sensor port
3. Upside down connection - The sensor connector is plugged in upside down (the connector has no locking mechanism to prevent incorrect orientation)

Solution

Option 1: Find new devices

1. Go to Settings → Hardware
2. Select the IO module where the sensor is connected
3. Run Find new devices
4. The module will scan for and register the new sensor

Option 2: Power Cycle the Module

If Find new devices doesn’t help:

1. Disconnect power from the IO module
2. Wait 10 seconds
3. Reconnect power
4. The module will reinitialize and detect the new sensor

Option 3: Check Connector Orientation

If the sensor still doesn’t work:

1. Unplug the sensor connector from the EXT port
2. Try plugging it in upside down (rotated 180°)
3. The connector has no locking mechanism, so it can be inserted incorrectly