Error code reference

Lennox Furnace Error Code 2+6

High fire pressure switch sensed closed prior to activation of combustion air inducer.

SourceLennox SL280UHV(X) Furnace - Service Manualp. 9

Diagnostic procedure

The full 2+6 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
1
First diagnostic step
Check that high prove switch is open without combustion air inducer operating; replace if defective.

SourceLennox G61MP Series - Service Manual: Gas Furnacep. 15

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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