PCG4 - Flashing Code 7

Article ID: 684
Last updated: 12 Apr, 2023

York Package Gas/Electric: PCG4

Re: Flashing Code 7

Code 7 = Failure to Sense Flame (3 Failed Ignition Attempts)

Qty Possible Causes:
1 Dirty Flame Sensor
Bad Glow Plug
1 Clogged Burners
No or Low Gas Pressure
1 Bad Gas Valve
Bad Ignition Control


1. Check Ignition Sequence

  • Initiate a call for heat from the thermostat and monitor the ignition sequence.
    • 1. The inducer motor should start with no difficulty.
    • 2. The pressure switch should close within a couple seconds of the inducer starting.
    • 3. The Gas Valve should open and the Sparker start sparking once the pressure switch closes.

2. Check Sparker

  • Turn off power to the furnace.
  • Remove the Spark Electrode from the burner compartment.
  • Check to make sure the Spark Electrode is not broken or badly corroded.
  • Check the Spark Wire to make sure it is not damaged.
    • Spark Electrode & Wire OK ⇒ Check for 24VAC at the Gas Valve during an ignition attempt.
      • 24VAC at Gas Valve + No Spark = Bad Control Board

3. Check Ignition

  • Visually inspect the burners during ignition.
    • The burners should light smoothly with little or no delay from the Spark Electrode to the flame sensor.
    • Make sure the flame sensor comes in good contact with the flame.

4. Check Gas Valve / Pressure 

  • Restart a call for heat and check for 24VAC across the two wires at the Gas Valve at the point of Ignition.
    • No Power = Bad Ignition Control
    • Power + No Ignition ⇒ Check Gas Pressure (below)
  • Check Inlet Gas Pressure
    • Minimum Pressure = 5" w.c. for Nat. gas, and 10" w.c. for LP.
      • Low Pressure = Gas Supply Issue
    • Re-apply power to the furnace and activate a call for heat.
    • Make sure the inlet gas pressure stays above minimum when the gas valve energizes.
      • Pressure Drops Below Minimum = Gas Supply Issue
  • Check Manifold Gas Pressure
    • Normal Pressure = 3 to 3.5" w.c. for Nat. Gas, 9 to 11" w.c. for LP.
    • Activate a call for heat and monitor the manifold gas pressure during an ignition attempt.
      • No Gas Pressure = Bad Gas Valve
      • Low Gas Pressure ⇒ Attempt to Increase Manifold Gas Pressure
        • Won't Increase = Bad Gas Valve
      • Normal Gas Pressure + No or Delayed Ignition = Clogged Burners ⇒ Remove burners and clean spreaders

5. Check Flame Sensor

  • Check the flame sensor reading when the burners ignite.
    • Normal Reading = 2 to 6 mA
    • Minimum acceptable reading = 1 MicroAmp
      • Low Reading = Dirty Flame Sensor ⇒ Clean the Flame Sensor & Re-check
  • CAUTION! Move meter leads back to "COM" and "V" before proceeding!
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Article ID: 684
Last updated: 12 Apr, 2023
Revision: 8
Access: Public
Views: 114
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