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Error code reference
Trane Furnace Error Code 8 Flash
Low flame sense signal - flame sense current is less than 1 micro-amp DC but still strong enough to allow operation.
SourceTrane XC80 Furnace - Service Manual: Variable Speed 2-Stagep. 30, 47
Diagnostic procedure
The full 8 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
Disconnect power; connect voltmeter leads in series with flame sensor set on DC micro-amp scale; verify flame sensor is correctly located.
SourceTrane XC80 Furnace - Service Manual: Variable Speed 2-Stagep. 30, 47
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
3 manuals in the MyPros+ library document this code for Trane furnace.
Models covered by the manuals that document this code
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