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Error code reference
Lennox Furnace Error Code DS1/DS2 Alternating Fast Flash
During ignitor warm-up only: improper main ground, broken ignitor or open ignitor circuit, or line voltage below 75 volts.
SourceLennox G60UH Series - Service Manual (Mid-Efficiency Gas Furnace)p. 15
Diagnostic procedure
The full DS1/DS2 Alternating Fast 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
1
First diagnostic step
Check ground, ignitor resistance (10.9-19.7 ohms for 18M34), and line voltage.
SourceLennox G60UH Series - Service Manual (Mid-Efficiency Gas Furnace)p. 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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Where this code is documented
1 manual in the MyPros+ library documents this code for Lennox furnace.
Models covered by the manuals that document this code
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