E05 displayed and thermostat cannot detect outdoor temperature; outdoor temp shows as dashes or N/A.

Safety: Turn off power to the HVAC system at the breaker before working on wiring.

• Step 1 – Confirm sensor feature: In the installer menu, verify that an outdoor sensor is configured only if one is actually installed. Disable the feature if no sensor is present.
• Step 2 – Inspect wiring at thermostat: Remove the thermostat and check the outdoor sensor terminals (often labeled OS1/OS2 or similar). Ensure wires are secure and not shorted.
• Step 3 – Inspect outdoor sensor: Locate the Johnson Controls outdoor sensor on the exterior wall. Check for physical damage, water intrusion, or UV‑damaged cable. Tighten connections.
• Step 4 – Measure resistance: With power off and sensor leads disconnected, measure resistance across the sensor. Compare to the manufacturer’s temperature‑resistance chart. Replace the sensor if readings are out of range.
• Step 5 – Check cable continuity: If the sensor tests good, test continuity of the cable run from thermostat to sensor. Repair or replace damaged cable.