Thermostat shows E09 and cannot detect the heating/cooling system type during setup.

Safety first: Turn off power to the HVAC system at the breaker before adjusting wiring.

• Step 1 – Confirm system type: Determine if your system is a conventional furnace + AC or a heat pump. Check the outdoor unit model number or documentation.
• Step 2 – Verify wiring against Geo manual: Remove the thermostat and compare each wire (R, C, W/W1, Y/Y1, G, O/B, AUX/E) to the Geo installation guide for your system type. Correct any miswired terminals.
• Step 3 – Check O/B circuit (heat pumps): If you have a heat pump, ensure the O/B wire is connected to the O/B terminal at both the thermostat and the air handler/heat pump control board. Inspect for breaks or shorts.
• Step 4 – Rerun equipment setup: In the thermostat menu, go to Settings > Equipment (or similar) and manually select the correct system type, number of stages, and whether you have a heat pump. Save and exit.
• Step 5 – Firmware update and reset: Update firmware via the Geo app if available. If E09 persists, perform a factory reset and repeat the guided setup carefully.
• Step 6 – Call a technician if unsure: If you cannot determine your system type or wiring, contact an HVAC professional to correctly configure the thermostat.