Thermostat displays E7 and may not recognize the connected HVAC equipment type; some modes may be unavailable.

Safety first: Turn off power to the HVAC system before changing wiring. Configuration changes in the menu can be done with power on.

• Review installer setup: Enter the installer or advanced settings menu on the Payne smart thermostat (see manual). Confirm the selected system type matches your equipment: Payne heat pump vs. Payne gas furnace with AC, number of stages, and aux heat type.
• Check O/B wiring: For heat pumps, verify the O/B wire from the Payne outdoor unit is connected to the correct O/B terminal on the thermostat and to the appropriate terminal on the indoor control board. Ensure the O/B setting (energize in cool vs. heat) matches the Payne heat pump requirements.
• Verify W/W2 and Y/Y2: Make sure first and second stage heat and cool wires are on the correct thermostat terminals and indoor control board terminals. Miswiring can cause the thermostat to detect an impossible configuration.
• Factory reset and reconfigure: Perform a factory reset on the thermostat, then carefully walk through the equipment setup wizard, selecting the correct Payne model type and stages.
• If E7 persists: With wiring and configuration verified, the thermostat's configuration memory or logic may be faulty. Replace the thermostat.