Thermostat reports E1 and will not control heating or cooling after installation or wiring change.

Safety first: Turn off power to the furnace/air handler and outdoor unit at the breaker before touching any thermostat or furnace wiring.

• Verify system power: Ensure the furnace/air handler breaker is ON and the service switch near the unit is ON. If the HVAC system has a low-voltage blade fuse on the control board, visually inspect it for a blown element.
• Check Rc/Rh wiring at Wyze base: Remove the Wyze thermostat display from the wall plate. Confirm the R (or Rc/Rh) wire is fully inserted into the R terminal and the terminal button is fully depressed, with 3/8" of bare copper making contact.
• Confirm R wire at furnace board: At the furnace/air handler control board, verify the same colored wire is firmly attached to the R terminal. Tighten the screw if loose.
• Measure voltage (advanced): With power restored and using a multimeter set to AC volts, measure between R and C at the furnace board. You should see ~24VAC. If not, the transformer or fuse may be faulty and a technician should be called.
• Check Rc/Rh jumper setting: Wyze thermostats typically auto-handle Rc/Rh internally. Ensure you have not manually split R into Rc and Rh unless your system truly has separate heating and cooling transformers.
• Power cycle: After correcting wiring, restore power at the breaker, reattach the thermostat display, and wait 3–5 minutes to see if the E1 code clears.