MEDIUM URGENCY

York 4 Red Flashes — Limit Switch Open

4 red flashes

Limit switch open — overheating. Usually restricted airflow.

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

What This Code Means

4 red flashes means the high limit switch has tripped due to overheating.

Likely Causes (Ranked)

Most common (~70%)

Dirty air filter

What: Restricted airflow.

How to check: Inspect filter.

Fix: Replace filter.

Shop parts

Common

Closed registers

What: Static pressure spike.

How to check: Open all vents.

Fix: Clear vents.

Common

Failed blower

What: Weak blower.

How to check: Feel airflow.

Fix: Replace motor.

Shop parts

Diagnostic Steps

Cut power 30s
Replace filter
Open vents
Watch for return
Check blower

Frequently Asked Questions

Why does York 4 red flashes keep coming?

Furnace overheating. Filter resolves most cases.

Same on Coleman?

Yes.

DIY?

Filter yes.

Related York Codes

Related Symptoms

Need More Help?

Try our interactive symptom diagnostic tool or browse York parts.

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