MEDIUM URGENCY

Lennox 7 Flashes — Burners Failed to Ignite Lockout

7 flashes

Burners failed to ignite — locked out after retries.

Brand: Lennox (Also covers Armstrong Air, Aire-Flo, Ducane) | Equipment: Gas Furnace

What This Code Means

7 flashes means the burners failed to ignite during the heat cycle and the control locked out after multiple attempts.

Likely Causes (Ranked)

Most common

Dirty flame sensor

What: Sensor can't detect flame.

How to check: Pull and check for soot.

Fix: Clean with emery cloth.

Shop parts

Common

Failed igniter

What: Igniter doesn't heat up enough.

How to check: Watch for orange glow.

Fix: Replace.

Shop parts

Common

Gas supply issue

What: Closed valve or low pressure.

How to check: Verify valve and other appliances.

Fix: Open valve or call utility.

Diagnostic Steps

Cut power 60s
Watch heat cycle
Clean flame sensor
Replace igniter if needed
Verify gas supply

Frequently Asked Questions

How to clear Lennox 7 flashes?

Cut power 60s. Fix the underlying issue or it returns.

What fixes it most often?

Cleaning the flame sensor — about 50% of cases.

Same on Armstrong/Ducane?

Yes.

Related Lennox Codes

Related Symptoms

Need More Help?

Try our interactive symptom diagnostic tool or browse Lennox parts.

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