Thermostat shows E18 and cannot join Zigbee/Z‑Wave or other smart home network (on compatible models)

Safety first: No mains wiring changes required.

Steps:

• Check the thermostat installer menu to ensure the smart home radio (Zigbee/Z‑Wave) is enabled.
• Update firmware on both the thermostat and the smart home hub (e.g., Home Assistant, SmartThings) to the latest versions.
• Reset the radio module on the thermostat (often via a specific reset option) and attempt pairing again following the hub's inclusion procedure.
• Ensure the thermostat is within range of the hub or a repeater device.
• If E18 persists and other devices pair normally, the thermostat's radio module may be defective and require replacement.