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*SD FAULT CODES AND TROUBLESHOOTING GUIDE
ALARM
ALARM
EXPLANATION
LED
BOARD
DISPLAY
TROUBLESHOOTING
DESCRIPTION
Pressure Switch
#2 and Collector
Switch Error
Pressure Switch #2
or collector switch
closed at intitial
call for heat
E3.3
Both inducer and collector switches are shorted
closed.
All pressure switches are checked at the
beginning of the heat cycle to be open. If the
control detects the inducer pressure switch #2 or
collector switch(PS2 on the board) closed, the
control will display 3.3
Pressure Switch #2
or Collector Switch
opens during hea
cycle
E3.4
1. Check for a blocked vent.
2. Check for faulty Inducer Pressure switch #2
or Collector Switch faulty.
3. Pressure switch hoses could be switched.
4. Check the wires, refer to the wiring diagram.
All pressure switches are checked at the
beginning of the heat cycle to be open. The
inducer pressure switch #2 and the collector
switch control signal is ignored throughout the
ignition cycle. The inducer pressure switch #2
and the collector switch is monitored 35 seconds
after ignition, both should be closed. If one or
both opens after 35 seconds after ignition , Error
3.4 will show on the LED Display and the heat
cycle stops.
Pressure Sensor
Errors
Pressure Sensor
Voltage too low
E4.1
1. Check pressure sensor wire assembly for
connection and wire damage.
2. Verify hose is from pressure sensor to the
bottom of the air inlet venturi is free of debris
and fully connected.
3. Check for faulty pressure transducer.
Control monitors the voltage from the pressure
transducer but ignores low voltage before the
inducer is activated. Once the inducer is activated,
a voltage from the pressure transducer .2 volts or
less is considered low and will show a 4.1 Error
code. If the voltage is between .2 and .7 volts
and pressure switch #1 fails to close at a call for
heat, Error 3.2 is reported
Pressure Sensor
Voltage too high
E4.2
Pressure sensor voltage is reading too high with
the inducer not running.
1. Check for faulty pressure sensor.
2. Measure the pressure. If the pressure is as
expected, replace the pressure transducer. There
should not be measurable amount of pressure
when furnace is idle.
At a call for heat the control monitors the pressure
sensor voltage. A voltage measured .7 volts or
higher will report a 4.2 Error
Pressure Sensor
out of span
E4.3
1. Check for incorrect Pressure Switch #1.
2. Pressure Switch #1 hole partially clogged.
3. Verify hose is from pressure sensor to the
bottom of the air inlet venturi is free of debris.
4. Faulty Pressure transducer- replace.
5. Check inducer for blockage.
6. Check for a faulty pressure switch.
The pressure transducer and Pressure switch #1
work together to ensure the control can continue
the ignition sequence. The inducer is initiated, and
pressure switch #1 closes. The control board
should read pressure transducer voltage output
between -.2 and -.7 Volts . If not, the control will
report a 4.3 Error code.
Blocked Vent Detected
Error-Inducer RPM
Limit exceeded
E4.4
1.Check the vent for proper installation and
blockage.
2. Check the inducer wiring/connection.
3. Check for a faulty inducer.
4. Check the condensate drain for a restriction.
The control will limit the inducer to 4700 RPM.
The control will stop the heat cycle if the inducer
RPM stays greater than 4700 RPM for 5 seconds.
Flame Sensed
when No Flame
should Be
Present
(Internal Lockout)
Flame Sensed when
No Flame should
Be Present
(Internal Lockout)
E05
Check to see if there is a flame present. If so,
the check for a faulty gas valve. If no flame is
present, control board should be replaced.
The control monitors output voltage to the flame
sensor and has detected the presence of voltage
when no call for heat is present.
Reversed
Polarity
Grounding
Voltage reversed
polarity
E6.1
Neutral and Hot Wire Switched
The control monitors voltage and can detect a
reversed polarity.
Bad Grounding
E6.2
1. Check all ground wires.
2. Make sure a field Ground is attached to the
factory provided stripped end wire
There 5 green grounds 1. Incoming field ground
2. Board ground to chassis 3 on the top right of
the control board. Ground to chassis on the 12
pin plug. 4. Inducer ground to chassis 5. Blower
motor ground to the blower housing.
Table 6. Continued
