Thermostat shows E6 and outdoor temperature reading is missing or incorrect; heat pump balance or lockout may not work

Safety: Turn OFF power to the outdoor unit at the disconnect and breaker before opening panels.

• Locate sensor: Find the Ruud outdoor temperature sensor, typically mounted near the outdoor unit coil or in the control compartment, connected to the outdoor control board.
• Inspect wiring: Check the sensor leads for cuts, UV damage, or loose connections at the control board terminals. Tighten terminals and repair or replace damaged wire.
• Resistance test: With power OFF, disconnect the sensor and measure its resistance with a multimeter. Compare the reading to the Ruud temperature/resistance chart for the ambient temperature. If the reading is far off, replace the sensor.
• Board input check: If a known-good sensor still reads incorrectly at the thermostat, the outdoor board's sensor input may be faulty and require board replacement by a technician.
• Reconfigure thermostat: After sensor replacement, reboot the system and verify that the thermostat now shows a reasonable outdoor temperature and E6 is cleared.