E4 displayed; unit may stop during heating mode or switch to protection mode

Safety first: Turn off power to the outdoor unit before removing any covers.

• 1. Inspect outdoor coil: Check if the condenser/evaporator coil (in heat pump mode) is excessively iced over. Light frost is normal; thick ice indicates a defrost issue.
• 2. Check T3 sensor placement: Locate the outdoor coil sensor clipped to the coil tubing. Ensure it is firmly attached and not hanging loose.
• 3. Test sensor resistance: Disconnect the T3 sensor from the outdoor PCB and measure its resistance at ambient temperature. Compare with Camry’s NTC chart. Replace if open, shorted, or out of specification.
• 4. Clear obstructions: Make sure the outdoor unit has good airflow and that snow, ice, or debris are not blocking the coil or fan.
• 5. Run a defrost cycle: After reassembly, restore power and run the unit in HEAT mode. The system should automatically enter defrost when needed. If E4 recurs, the defrost logic on the outdoor PCB may be faulty.

Recommendation: Persistent E4 faults after sensor replacement require professional diagnosis of the Camry outdoor control board and refrigerant system.