trouble shooting
COMBITHERM® CT PROFORMANCE™ SERIES • STEP-BY-STEP PROCEDURES • MN-35948 • 57.
ERROR CODES
Error 
Code
Error Call Out in Display Description of Error Possible Cause
E51
No Water In Boiler Lower water level probe B2 is 
not satisfi ed within 5 minutes,  
after water solenoid valve Y1 
is activated
— Water supply is shut off.
— Low water pressure.
— Boiler drain cap missing.
— Boiler drain pump defective.
— Drain pump elbow leaking.
— Water level probe has calcium build up.
— Double water solenoid valve defective (Y1).
— Relay board, high voltage, defective.
E53
Fan Motor High 
Temperatures
Fan motor does not spin, 
result in over-heating, 
detected by motor coil safety 
thermo element. Temperature 
more than 320°F (160°C).
— Motor high limit open or wired incorrectly.
— If LED on motor control fl ashes, see error codes  
for motor control.
— Motor or fan wheel locked.
— Fan wheel damaged.
E54
Lower Fan Motor High
Temperature
Lower fan motor does not 
spin, result in over-heating, 
detected by motor coil safety 
thermo element. Temperature 
more than 320°F (160°C).
— Motor high limit open or wired incorrectly.
— If LED on motor control fl ashes, see error codes 
for motor control.
— Motor or fan wheel locked.
— Fan wheel damaged.
E55
Vent Not Open 60 seconds after the venting 
motor is activated the vent 
motor safety switch did not 
open.
—  Alignment issue between motor cam and vent 
motor safety switch (micro switch).
—  Faulty vent valve (motor).
—  Faulty vent valve safety switch (micro switch).
E56
Vent 2 not open 60 seconds after the venting 
motor is activated the vent 
motor safety switch did not 
open.
—  Alignment issue between motor cam and vent 
motor safety switch (micro switch).
—  Faulty vent valve (motor).
—  Faulty vent valve safety switch (micro switch).
E57
No Rinse Water Flow switch for solenoid 
valve Y4 does not detect any 
water fl ow for a minimum of 
60 seconds.
—  Water supply is shut off.
—  Low water pressure.
—  Flow switch is dirty or defective.
—  Double water solenoid valve defective (Y3).
—  Relay board, high voltage, defective.
E88
Lower Gas Ignition Failure Reset output from Ignition 
Module is ON
— Hot surface ignitor not functioning.
— No gas supply.
— Flame sensor not functioning.
— Faulty ignition control.
E89
Upper Gas Ignition Failure Reset output from Ignition 
Module is ON
— Hot surface ignitor not functioning.
— No gas supply.
— Flame sensor not functioning.
— Faulty ignition control.
E90
Lower Gas Combustion 
Blower Not at Speed
Speed is too 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.
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