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Error code reference
Lennox Furnace Error Code 5
Watchguard - burner failed to light, exceeded maximum number of retries or recycles.
SourceLennox EL180DFE - Service Manual: Mid-Efficiency Gas Furnacep. 8
Diagnostic procedure
The full 5 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
Wait 60-minute reset period; check ignitor, gas valve, and flame sensor.
SourceLennox EL180DFE - Service Manual: Mid-Efficiency Gas Furnacep. 8
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
2 manuals in the MyPros+ library document this code for Lennox furnace.
Models covered by the manuals that document this code
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