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F6

F6 — Indoor coil outlet temperature sensor error (T2B)

Lennox · Air Conditioning

What does F6 mean?

This error code signifies a problem with the indoor coil outlet temperature sensor (T2B). This sensor measures the temperature of the refrigerant leaving the indoor coil.

Common Causes

  • Faulty indoor coil outlet temperature sensor (T2B)
  • Loose or damaged wiring to the sensor
  • Issues with the indoor unit's main control board

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Inspect the wiring and connections for the indoor coil outlet temperature sensor (T2B).

  2. 2

    Verify the sensor's resistance value against the specifications in the manual.

  3. 3

    If the sensor appears faulty, replace it.

  4. 4

    If the sensor is functioning correctly, the indoor unit's control board may be the issue.

Browse all codes in this manual (57)
Verified technical data. Last updated: April 2026

Related Faults

E0E0 — Indoor unit EEPROM error (MMDB Indoor Units)E1E1 — Communication error between indoor and outdoor units (MMDB Indoor Units)E3E3 — Indoor fan speed error (MMDB Indoor Units)
Source: Lennox Air Conditioning
Open Manual (Page 6)Search more codes in this manual