Thermostat shows E04 and cannot detect the remote room sensor or wireless temperature puck paired with the Ngenic system.

Safety: Only handle battery-powered remote sensors. Do not open mains-powered modules.

• Replace batteries: Open the Ngenic remote sensor housing and replace the batteries with the specified type, observing polarity.
• Check distance and obstacles: Move the remote sensor closer to the thermostat or control module, avoiding thick concrete walls or metal cabinets.
• Eliminate interference: Keep the sensor away from large Wi‑Fi routers, DECT phones, and other RF devices that may interfere.
• Re-pair the sensor: On the thermostat/app, go to Devices → Add/Pair Sensor and follow the instructions to re-register the remote sensor.
• Restart system: Power-cycle the control module and thermostat to refresh the radio link.

If E04 remains after battery replacement and re-pairing, the radio module in either the remote sensor or the Ngenic control module may be defective and require replacement.