51 Page
ERROR CODES
-General-
• The units are self-diagnostic for safety and convenience when troubleshooting.
• If there is a problem with the installation or the unit, the error code will be displayed on the 
temperature controller and remote controller.
• Consult with the table on the following pages for the description of each error code.
-Single unit Installa ons-
Example: If your unit has the “321” error code (which signifies an inlet thermistor failure)
• Indicator on the temperature
     controller or Remote controller : “321”willbedisplayedonthescreeninitsentirety.
• Green LED on the computer board: The green LED on the computer board will be
                                                                 blinking two times.
-Easy-Link System-
(For the 540 (T-H3) models only)
Error codes will be displayed differently with units installed within an Easy-Link System, not only to show 
what the error code is, but to also indicate which unit within the system has the error code.  Below is a 
sample of how the same error code is displayed in an Easy-Link System.
Example: If Unit #2 has the “321” error code (inlet thermistor failure)
• Indicator on the temperature controller
     (Parent unit) or Remote controller :
“321”and"2"willintermittentlyflashon
                         the display.  And it shows that Unit #2 has
                         the error.
Troubleshoo ng
Owner's Guide
Unit #Error code
• Unit #2:       "321" will intermittently flash on
                          the display.  And the green LED on 
                               the computer board will be blinking
                          two times, just like in the single
                          unit example.
Error code
Error code on the computer board
240 (T-H3J) and 340 (T-H3S) models
Green LED
540 (T-H3) models
Green LED
Error code indicator on 
the temperature controller
Error code indicator on the remote 
controller 9008172005 (TM-RE40) 
Unit #1
PARENT
Unit #2
 CHILD
Unit #4
 CHILD
Unit #3
 CHILD
• Unit #3 
     and #4:        These units will not display anything, as the error code does not pertain to them.