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Trane E6.3: Igniter relay fault or igniter open/shorted

Ref. TRANE-E6-3 · From the Trane furnace manual · Updated 2026-10-23

Status codeE6.3Trane
What it means

Igniter relay fault or igniter open/shorted.

Call a profurnace
How it shows: 7-segment display alternates with mode: E6.3

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§1Likely causes

  • Igniter relay stuck on control
  • Igniter open or shorted
  • Damaged igniter harness or loose connectors

§2Safe DIY steps

  1. Technicianverify igniter harness and connectors
  2. Techniciancheck igniter resistance (37-70 ohms at ~75F); replace igniter or IFC as indicated
Safety firstIf you smell gas, do not touch any electrical switch or use a phone in the building; leave immediately and call your gas supplier from outside. Turn off electrical power at the furnace switch or breaker before opening any panel, and never bypass or jumper a limit, rollout or pressure switch. Gas valve, burner, venting, wiring and control-board work should be done by a licensed HVAC technician.

§3When to call a pro

Call a licensed HVAC technician: igniter testing involves line voltage.

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§4Other Trane codes

E01Trane

Loss of the IRQ or other internal failures (internal furnace control error).

E04Trane

Open limit: main thermal limit, flame rollout switch, or reverse airflow switch.

E05Trane

Flame detected when it should not be present.

E06Trane

Voltage reversed polarity or bad grounding.

E08Trane

Low flame current, but still strong enough to allow operation.

E09Trane

Open inducer limit switch or condensate pressure switch.