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Error code reference
Trane Furnace Error Code Solid ON
Internal control failure (ERR 18) - internal control failure within IFC.
SourceTrane XC80 Furnace - Service Manual: Variable Speed 2-Stagep. 30
Diagnostic procedure
The full Solid ON 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
Replace IFC.
SourceTrane XC80 Furnace - Service Manual: Variable Speed 2-Stagep. 30
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 Trane furnace.
Models covered by the manuals that document this code
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