HIGH URGENCY

York 1 Red Flash — Flame Sensed With Gas Valve Closed

1 red flash

Flame detected when gas valve closed — leaky valve.

Brand: York (Also covers Coleman, Luxaire) | Equipment: Gas Furnace

What This Code Means

1 red flash means the flame sensor detects flame even when the gas valve is closed. Usually a leaky or stuck-open gas valve.

Most common

What: Valve doesn't fully close.

How to check: Tech test.

Fix: Replace gas valve.

Shop parts

Less common

What: Board misreads flame signal.

How to check: Tech diagnostic.

Fix: Replace board.

Shop parts

Same on Coleman/Luxaire?

Yes — Johnson Controls sister brands.

DIY?

No — gas valve work professional only.

How urgent?

Very urgent — same-day service.