29
*SD FAULT CODES AND TROUBLESHOOTING GUIDE
ALARM
ALARM
EXPLANATION
LED
BOARD
DISPLAY
TROUBLESHOOTING
DESCRIPTION
Igniter
Failure
Error
Ignitor open or
Igniter relay fails
E6.3
Damaged open ignitor or internal control relay.
1. Check wiring, verify the ignitor is connected.
2. Watch through sight glass to see if it glows
during ingnition.
3. Measure the ignitor resistance, if less than 100
ohm then its probably good. If greater that 100
ohm, replace the ignitor.
4. If the ignitor is good then ignitor relay is stuck
open or closed.- Replace the board.
Controls senses if the ignitor is open.Measure
ignitor resistance if less than 100 ohms then
probably good. If ignitor is good then board needs
to be replaced.
External Gas
Valve Error
(Internal Lockout)
Power at Gas Valve
detected without
a call for heat
E7.1
1. Check voltage on gas valve when there is not
call for heat. If voltage is present, check wiring.
The gas valve should not have voltage present
without a call for heat.
2. If the E7.1 is still present after verifying no
voltage at the gas valve without a call for heat,
a relay is stuck on the control board. - Replace
the board.
The control senses 24V output to the gas valve
at all times. Verify power is not getting to the gas
valve from another source. If not , relay is stuck
on the board -replace the board
Relay output
to HLO
energized
Output Relay to Limit
Switches Energized
without a call for heat
E7.2
1. Check for voltage at the limit switches when
there is no call for heat. If voltage is present, check
wiring. 2. If E7.2 is still present after verifying
no voltage at the limits without a call for heat, a
relay is stuck on the board. - Replace the board.
The control senses 24V output from internal
relays at all times. If power is detected at the
HLO output on the 12 pin plug at any time even
without a call for heat E7.2 is displayed.
Low
Flame
Sense
Flame current is low,
but still strong enough
to allow operation
E08
Eo8 would show up in the last 6 fault codes. Check
for dirty flame probe. Replace if necessary. Check
for a faulty flame sensor.
Control monitors flame current and if low then
E08 is reported but will still allow normal furnace
operation.
Open Limit
Switch Error
Open Limit
E9.1
Check wiring and limit switches
Limit Switch(es) in HLO to HLI detected open
during heat cycle
Open Inducer
Limit Switch
Open Inducer
Limit Switch
E9.2
Check inducer limit switch and wiring.
Open Inducer Limit Switch detected during heat
cycle(ILI)
Inducer
Communication
Error
Inducer or control
board has failed
E10
This is an internal board function. Replace the
board
This is an internal board function.
Replace the board
Internal Gas
Valve Error
Failure of gas valve
to energize
E11
Replace the Board
Gas valve error. Control monitors the power the
gas valve should be using and senses if the valve
is open or closed
Gas valve relay
stuck closed
Gas valve error. Control monitors the power the
gas valve should be using and can sense if the
valve is open or closed
Failure of HLO
output to energize
Relay on the board is not supplying 24V. The
control monitors 24V outputs to internal relays.
If a relay is not energized in the heat sequence,
E11 is displayed on the control.
Open Fuse
Error
Open fuse
E12
Check the fuse. If the fuse is good, replace the
board. If the fuse is open, check for shorts, and
replace the fuse.
If supply voltage of 110V is still be present and
the fuse is blown, E12 is displayed on the control.
Table 6. Continued
