E09 displayed and thermostat cannot detect the external wireless receiver or gateway.

Safety first: Turn off power to the receiver module at the breaker before opening its cover.

• Step 1 – Check receiver power: Verify that the Atlantic receiver or gateway has power (LED indicators on, no tripped breaker). Restore power if off.
• Step 2 – Reduce distance: Temporarily move the thermostat closer to the receiver (same room if possible) and see if E09 clears. If it does, RF range or obstacles are the issue.
• Step 3 – Remove interference: Keep Wi‑Fi routers, cordless phone bases, and large metal objects away from the receiver and thermostat. Avoid installing the receiver inside metal cabinets.
• Step 4 – Re‑pair devices: Put the receiver into pairing mode (press and hold the link button until LED flashes), then initiate pairing from the thermostat menu. Wait for confirmation that the link is established.
• Step 5 – Check RF antennas: On some models, the receiver has an external antenna wire. Ensure it is intact and not cut or coiled tightly.
• Step 6 – Replace faulty unit: If E09 persists at close range with correct pairing steps, either the thermostat RF module or the receiver RF module is defective. Substitute with a known‑good unit to identify which part to replace.