HIGH URGENCY

Trane Furnace 5 Flashes — Flame Sensed With Gas Valve Off

5 flashes

Flame detected when gas valve should be closed — leaky valve.

Brand: Trane (Also covers American Standard) | Equipment: Gas Furnace

What This Code Means

5 flashes means the flame sensor detects flame even when the gas valve is supposed to be off. Typically a leaky or stuck-open gas valve.

Most common

What: Valve doesn't fully close, allowing fuel to keep burning.

How to check: Tech valve test; visible flame after heat call ends.

Fix: Replace gas valve.

Shop parts

Less common

What: Board falsely reports flame signal.

How to check: Tech measures flame sensor signal at board.

Fix: Replace board.

Shop parts

Is Trane 5 flashes dangerous?

Yes — uncontrolled flame, possible gas leak. Shut off gas supply immediately.

Can I fix this myself?

No — gas valve work requires licensed pro.

Same on American Standard?

Yes — same code, same severity.