Error code reference

Lennox Furnace Error Code 2+3

Low fire pressure switch sensed open; 80%: check blocked exhaust.

SourceLennox SL280DFV Series Furnace - Full Service Manualp. 7

Diagnostic procedure

The full 2+3 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 blocked exhaust.

SourceLennox SL280DFV Series Furnace - Full Service Manualp. 7

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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

7 manuals in the MyPros+ library document this code for Lennox furnace.

Models covered by the manuals that document this code

More models are covered than are listed here.

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The full 2+3 procedure

Where this code is documented

Models covered by the manuals that document this code

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