2.1 Fault Code
Cycle power to furnace.
Connect manometer to
manifold pressure
connector and call for 1
st
stage heat
Does gas ignite?
YES
Is manifold pressure
~1.7"WC (NG)
~6.0"WC (LP)
YES
Do all burners
ignite within 4
seconds?
Check igniter
posi!on and correct
if needed. Check
opera!on
Adjust manifold gas pressure to
~1.7"WC (NG)
~6.0"WC (LP)
Check opera!on
NO
NO
YES
Measure flame
current. Is flame
current less than 0.5
micro-amp?
YES
Possible Causes
Dirty Sensor
Dirty burners
Poor grounding
Sensor loca!on
Wire connec!ons
Flame sensor is good
NO
DEFINITION
RETRY Lock Out = 3 unsuccessful tries for igni!on
within a single call for heat. Lockout period is for
one hour
Flame has never been sensed
All gas appliances in the home should be turned
on to verify gas pressure
Disconnect electrical
power to furnace.
Connect manometer
to inlet gas pressure
connector
Is inlet gas pressure above
13.8" WC or less than
nameplate minimum ?
NO
Correct inlet gas pressure.
Maximum pressure is 13.8"WC
Check opera!on
YES
To measure flame current, use a VOM set to DC micro-
amps. Connect voltmeter leads in series with flame
sensor circuit, see illustra!on
Possible causes:
Burner alignment
Dirty burners
Low manifold pressure
Is any gas
pressure
present?
NO
YES
Possible causes
Switch OFF?
No voltage to GV
Debris in gas valve
NO
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