What It Means
Incorrect electrical line polarity or improper ground detected.
Trane Furnace
Trane Furnace Error Code 6 Flashes
Troubleshooting guide for the Trane Furnace system fault 6 Flashes.
Possible Causes
- Reversed hot and neutral line wiring.
- Improper or missing system ground.
- Internal failure in low-voltage transformer.
Not sure which one it is — or if it's none of these? Try ACLogics today.
Disclaimer: This information is for general reference. Error codes can vary by model and production year. Always refer to your machine's specific manual and the information printed on the unit itself.
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Full Diagnosis
Line polarity or grounding issue. The control board senses incorrect electrical polarity or a grounding problem.
All Recorded Causes
Turn off power and verify the furnace’s hot and neutral wires are properly connected (no reverse polarity). Check the system ground. Inspect the transformer as well, as an internal failure can cause polarity errors. Correct any wiring issues; if unclear, have an electrician or HVAC pro address it.
Verify Before Replacing Parts
- Confirm the exact Trane model family and furnaces context before acting on a generic code description.
- Start with line voltage, low voltage, and board output checks in sequence so the fault is isolated cleanly — the data plate flags turn off power and verify the furnace’s hot and neutral wires are properly connected (no r….
- Inspect connectors, relay outputs, and any recently replaced electrical parts for mismatch or loose fit, and verify check the system ground.
- After the correction, run the system long enough to confirm the furnaces fault does not return under normal load.
Still unsure about this fault?
ACLogics walks you through Trane Furnace diagnostics step-by-step — so you confirm the cause before swapping parts.
