Error code reference

York Furnace Error Code 1 Flash

Flame sensed without a call for heat.

SourceYork P*XU/G9D-UP Furnace - Full Service Manualp. 8

Diagnostic procedure

The full 1 Flash procedure

Step 1 is visible so you can confirm you are on the right page. The remaining steps, the ones that tell you whether to actually replace a part, unlock with any pass.

MyPros+ · DiagnosticsStep 1 preview

First diagnostic step

Check for gas valve stuck open, gas valve slow closing, incorrect wiring (gas valve energized when it should not be), defective ground, or flame rod shorted to ground.

SourceYork P*XU/G9D-UP Furnace - Full Service Manualp. 8

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More steps, wiring diagram references, and verified part numbers

Includes expected resistance and voltage values, connector pinouts, and supersession notes for replacement parts.

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Where this code is documented

1 manual in the MyPros+ library documents this code for York furnace.

Models covered by the manuals that document this code

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The full 1 Flash procedure

Where this code is documented

Models covered by the manuals that document this code

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