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MEDIUM URGENCY

Goodman 4 Flashes — High Limit Switch Open

4 flashes

High limit switch open — overheating. Usually a dirty filter.

Brand: Goodman (Also covers Amana, Daikin)  |  Equipment: Gas Furnace

What This Code Means

4 flashes means the high limit switch has tripped due to overheating in the heat exchanger.

Likely Causes (Ranked)

Most common (~70%)

Dirty air filter

What: Restricted airflow lets heat build up.

How to check: Hold filter to light.

Fix: Replace filter, cycle power.

Shop parts
Common

Closed registers

What: Static pressure spike.

How to check: Open all vents.

Fix: Clear vents and returns.

Common

Failed blower

What: Weak blower can't move heat.

How to check: Feel airflow.

Fix: Test capacitor, replace motor.

Shop parts
Less common

Faulty limit switch

What: Switch fails in open position.

How to check: Tech tests resistance cold.

Fix: Replace switch.

Shop parts

Diagnostic Steps

  1. Cut power 30s
  2. Replace filter
  3. Open all vents
  4. Wait for cooldown
  5. Watch for return

Frequently Asked Questions

Why does Goodman 4 flashes keep coming?
Furnace is overheating. Filter resolves 70%+ of cases.
Same on Amana?
Yes — sister brands using same control board.
How to reset Goodman limit switch?
Most auto-reset on cooldown. Cut power 30s to clear code.

Related Goodman Codes

Goodman Error Code 3 FlashesGoodman Error Code 6 Flashes

Related Symptoms

Furnace Keeps Shutting OffFurnace Short CyclingFurnace Blowing Cold Air

Need More Help?

Try our interactive symptom diagnostic tool or browse Goodman parts.

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