Trane ReliaTel Diagnostic Manual page 72

Thermostats and Sensors
Error Codes
Lock Symbol
72
Main processor error
Software version conflict
Communication error
Temperature input outside valid
operating range (32ºF–122ºF [0ºC–50ºC])
Indicates that the keypad is locked
Replace sensor.
Replace sensor.
Replace sensor.
Replace sensor if space temperature is
within valid range.
The lock symbol appears if you try to
adjust a setting that cannot be changed.
RT-SVD03G-EN