Service Manual

22
Error
Code
Definition of Code
Cause of Problem and Actions Taken to Correct
105
Flame detected out of
sequence
• Check to see if flame is present inside the combustion chamber before or after
the ignition cycle.
• If so, check to make sure the gas valve is wired correctly.
• Check for voltage at the gas valve connection.
• Replace the gas valve if defective.
• If no flame is visible outside of the ignition sequence/run cycle, then make sure
the flame sensor is wired to the correct terminal.
• Make sure the ignition cable is not crossing the flame sensor wire or ignition
ground wires.
• If problem persists and all other checks have been verified, replace the control
module.
109,
110
Ignition Failure
Occurred.
• Burner failed to light or stay lit after 4 retries.
• Hold condition – will reattempt ignition after 15-minute waiting period. A log will
be stored in service history.
• Check gas valve wiring and gas valve operation during the ignition cycle.
• If burner lights but quickly goes out, check the flame sensor wire or the flame
sensor.
• If the flame sensor rod is badly corroded with deposits, clean with sandpaper or
replace.
• Check the inlet gas supply to make sure the pressure is sufficient and does not
drop after the gas valve opens.
• Make sure the combustion blower is operating during the ignition and run cycle.
• Check the venting system to make sure the inlet and exhaust terminals and
venting system is not blocked.
122,123
Light-off Rate Proving
Failed
• If blower speed is not verified from the PWM (Pulse Width Modulation) signal
within 5 minutes, the previously described error code “62” changes from a hold
condition to this lockout code condition
• Check the harness and pin terminals for a good connection to the control module.
• Replace the blower or control module if the wire harness is good.
172
Water temperature
sensor resistance
invalid
• Hold 93 will be displayed if this value remains out of range
• Measure the resistance of the water temperature sensor and compare it with the
tank temperature using the chart below.
NOTE
• If there is no display, check primary/secondary voltage
• Before troubleshooting always verify the following
o Gas inlet pressure
o Static to dynamic gas pressure drop
o No vent and intake restrictions
o All wire connections are tight
o No grounded wires or missing grounds
o No water leaks
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