Trane furnace E6.3: Igniter relay failed, or igniter open

E6.3 covers two possibilities that Trane lists explicitly: the igniter relay on the control has failed, or the igniter itself is open. One is a board fault and one is a consumable part.

Applies to: Trane and American Standard S9V2 two-stage condensing variable speed gas furnaces with a seven-segment integrated furnace control display, per Installer's Guide 18-CE01D1-1E-EN.

What it means

The control closes a relay to energise the hot surface igniter and monitors the circuit. E6.3 says that circuit is not behaving, and Trane names both ends of it rather than assuming. An open igniter is the far more common of the two — silicon carbide igniters are brittle, fail open, and are genuinely consumable parts that every furnace using one will need replaced eventually. A failed igniter relay is a control board fault and a much more expensive repair. The distinction matters commercially as well as technically, because replacing a board when the igniter was the problem is an expensive mistake in the wrong direction.

Most common causes

• A cracked or failed hot surface igniter, which fails open. This is the usual cause.
• Igniter wiring damaged, loose, or unseated at the connector.
• A failed igniter relay on the control board.
• Damage from previous service work, since igniters break easily when handled.
• An igniter at the end of its service life on an older furnace.

How to diagnose it

1. Note whether the igniter glows at all during a start attempt, if the furnace has a sight glass.
2. Note the age of the furnace and whether the igniter has ever been replaced.
3. Note whether the fault began immediately after a service visit.
4. The igniter should be measured before either it or the board is replaced.

How to fix it

1. Technician work in the burner compartment.
2. Ask that the igniter be measured first. It is the cheaper and far more likely of the two causes Trane names.
3. A replacement igniter must be the correct part for the model.
4. Only if the igniter measures good does the relay on the board become the suspect.

Notes

Because the code covers both a cheap part and an expensive one, it is worth asking explicitly which was measured rather than which was replaced.

Related

• E2.1 — Retry exceeded — flame never sensed
• 9 flashes — Ignitor circuit problem, or low neutral to 24 V common voltage

All codes for this manufacturer

Trane and American Standard furnace flash codes — every code, with what differs between models.

Sources

• Trane Installer's Guide 18-CE01D1-1E-EN — S9V2 two-stage condensing variable speed furnaces, Integrated Furnace Control Display Codes