Appliance Diagnostic

York Furnace Code d3 - Low Pressure Switch Open Fault

Code d3 indicates pressure switch opened during active burner operation, dropping out flame for safety.

What Caused This Error?

The control system reports d3 when the monitored condition described by the error code is outside the expected operating range. In this case, the most likely trigger is water backed up in draft inducer housing. Other common contributors include blocked vent terminal screen and failing inducer motor bearings.

Step-by-Step Diagnostic Check

  1. Clear blocked drain lines connected to furnace collector box.
  2. Inspect flue pipe outdoors for leaves or ice buildup.
  3. Check vacuum hose for moisture accumulation or cracks.
  4. Replace draft inducer motor assembly if dragging.

Did this fix your York d3 error?

Most Likely Replacement Part

Draft Inducer Assembly

OEM Part #: MODEL-SPECIFIC

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