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CRITICAL URGENCY

York 5 Red Flashes — Roll Out Switch Open (SAFETY)

5 red flashes

Flame rollout switch tripped — possible cracked heat exchanger and CO risk.

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

SAFETY: Cracked heat exchanger releases CO. Evacuate and call 911 if anyone has headache, dizziness, nausea.

What This Code Means

5 red flashes means the flame rollout switch has opened. Flames are escaping the burner enclosure — a serious combustion problem.

Likely Causes (Ranked)

Common and serious

Cracked heat exchanger

What: Crack lets flames escape.

How to check: Tech inspection only.

Fix: Replace HX or furnace.

Shop parts
Common on 90%+ AFUE

Plugged secondary HX

What: Condensate buildup blocks passages.

How to check: Tech inspection.

Fix: Clean or replace.

Shop parts
Common

Blocked flue

What: Birds, ice, dropped pipe.

How to check: Inspect exhaust.

Fix: Clear.

Shop parts
Less common

Failed inducer

What: Poor draft.

How to check: Listen.

Fix: Replace.

Shop parts

Diagnostic Steps

  1. STOP — don't keep resetting
  2. Shut off gas
  3. Verify CO detector
  4. Call licensed HVAC tech

Frequently Asked Questions

Can I reset and keep running?
No — CO risk with cracked heat exchanger.
Cost to repair?
Heat exchanger $500-1200 labor; often cheaper to replace furnace.
Same on Coleman/Luxaire?
Yes.

Related York Codes

York Error Code 4 Red Flashes

Related Symptoms

Furnace Smells GasFurnace Pilot Yellow Flame

Need More Help?

Try our interactive symptom diagnostic tool or browse York parts.

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