Complete Fault Code List
Description of the Fault Corrective Action
2 No flame at start-up
A flame failure occurred during lightoff.
1. Check the wiring of the ignition transformer, pilot valve, and main valve(s).
2. Ensure manual shutoff valves on the pilot gas line and main gas line are open.
3. Check the fuel / air ratio at lightoff.
4. Check the flame detector signal in the presence of a known flame source. Replace the flame detector if it
does not produce the anticipated signal.
3 Air pressure switch open
The air pressure switch connected to terminal X3-02.1 is open, causing a fault. Ensure the setpoint of the
switch is set to an appropriate value. Check the wiring of the air pressure switch. If no air pressure switch is
being used, place a jumper from terminal X2-01.3 to X3-02.1.
4 Extraneous light
An extraneous light (flame signal present when there should be none) fault occurred.
1. Ensure that the source of light is not a flame. If it is, take corrective action immediately.
2. Ambient light can cause an extraneous light fault. Ensure the flame scanner is viewing a dark area.
3. UV scanners typically fail on, giving a false flame signal. Remove UV scanner and cover the bulb to
ensure it is not seeing any light. Look inside the bulb and see if any purple arcs of electricity are occurring
between the electrodes in the bulb. If there are, replace the UV scanner.
5 Air pressure switch closed
The air pressure switch connected to terminal X3-02.1 is closed before the blower output is energized in
phase 22, causing a fault. Ensure the setpoint of the switch is set to an appropriate value. Check the wiring
of the air pressure switch. If no air pressure switch is being used, place a jumper from terminal X2-01.3 to
X3-02.1.
6 Actuator position fault
The required position feedback from the connected SQM… actuator was not received.
1. Ensure the potentiometer on the SQM… actuator is wired correctly.
-For counter-clockwise actuators (SQM40…, SQM50…), terminal "c" on the potentiometer should be wired
to terminal X66.1 on the LME7, and terminal "a" on the potentiometer should be wired to terminal X66.3 on
the LME7.
-For clockwise actuators (SQM41..., SQM50...R), terminal "a" on the potentiometer should be wired to
terminal X66.1 on the LME7, and terminal "c" on the potentiometer should be wired to terminal X66.3 on
the LME7.
2. Ensure the SQM... actuator is wired properly to the LME7, especially the position feedback on terminal
X2-09.4 of the LME7.
3. Ensure no mechanical stops are preventing the actuator from reaching its expected position.
4. While not common, heavy vibration on the actuator can wear a track in the position feedback
potentiometer. If the fault always occurs at the same actuator position, the actuator may need to be
replaced, and the vibration needs to be reduced to avoid having a similar issue with the new actuator.
Section 7 Page 3 SCC Inc.
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