trouble shooting
COMBITHERM® CT PROFORMANCE™ SERIES • STEP-BY-STEP PROCEDURES • MN-35948 • 58.
ERROR CODES
Error 
Code
Error Call Out in Display Description of Error Possible Cause
E91
Upper Gas Blower Not at 
Speed
Speed is to slow. — Power supply cable is not connected to blower 
motor
— Speed control cable is not connected to blower 
motor
— Blower motor is blocked, rotation is impeded, or 
motor is faulty
— Faulty control board
E92
Communication Error
CB does not properly 
respond
Twelve (12) instances of 
no-response from the relay 
board (CB) to the display 
board (IB).
— Check CAN cable connections mentioned 
below.
— CAN cable defective.
— Relay board, low voltage, connector defective.
— Display board connector defective.
E94
Communication Error,
TO Interface Board
No signal transfer for more 
than 5 seconds between the 
Interface Board (IB) and the 
Control Board (CB).
— Check CAN cable connections mentioned 
below.
— CAN cable defective.
— Relay board, low voltage, connector defective.
— Display board connector defective.
E100
One or more maintenance 
reminder has timed out.
When any maintenance 
reminder has expired without 
action having been taken by 
the operator.
— Enter maintenance reminder screen and 
address the item that has timed out and reset
E101
Ventless Hood Fault - No 
Pressure
If the power switch or 
pressure switch is not closed.
—  Check power switch is on.
—  Check vent motor is turning in the proper 
direction.
— Pressure switch is mis-wired or defective.
— Filter(s) require cleaning or replacement
E102
Ventless Hood Fault — 
Filters Not Present
If the air fi lter switches are 
not closed.
—  Check fi lters are installed and properly seated.
—  Check fi lter switches are not damaged, 
defective or dislodged.
E103
Option Board Doesn’t Send 
Switch Setting
OB not communicating its 
switch settings to the CB.
— Check CAN cable connection between OB and 
CB.
— Ensure CB dip switch is set to see an OB.
— Incompatible OB and CB software (update 
software).
— OB defective.
— CB defective.
E104
Option Board Not 
Communicating
Option board is not 
communicating with CB.
— Check option board CAN connection at CB and   
OB.
— Defective OB.
— Defective CB.
E105
No or Low Water Pressure Water pressure switch not 
activated.
— Water supply not connected.
— Water supply is shut off.
— Water supply to unit blocked or obstructed
— Faulty or miswired pressure switch
E106
Boiler Drain Pump Fault Hall effect or rotational 
sensor is not sending a signal 
to the relay board
— Drain pump motor not running or defective.
— Hall effect sensor broken or incorrectly wired.
— Motor improperly wired.
continued on next page