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Error code reference
Lennox Furnace Error Code 4+6
Watchguard: Flame sensed out of sequence; flame not present (auto retry after 60 min).
SourceLennox SL280UHV(X) Furnace - Service Manualp. 9
Diagnostic procedure
The full 4+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 flame sensor for contamination or grounding issues.
SourceLennox G60UHV(X) Series Furnace - Full Service Manualp. 18
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
- C33-18A-2F
- C33-24A-2F
- C33-30A-2F
- C33-36A-2F
- EL280UH070P24A
- EL280UH070P36A
- EL280UH070XP36A
- EL280UH090P36B
- G60UH-1
- G60UH-24A-045
- G60UH-24A-045X
- G60UH-24A-070
- G60UH-36A-070
- G60UH-36A-070X
- G60UH(X)
- G60UHV-36A-070
- G60UHV-36A-070X
- G60UHV-36B-090
- G60UHV-60C-090
- G60UHV-60C-090X
- G61MP-36B-045
- G61MP-36B-070
- G61MP-48C-090
- G61MP-60C-090
More models are covered than are listed here.
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