LOW URGENCY

Lennox 8 Flashes — Burners Lost Flame Too Many Times

8 flashes

Flame established but kept dropping out — usually flame sensor.

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

What This Code Means

8 flashes means the burners did ignite but lost flame multiple times during operation. Typically a flame sensor issue.

Likely Causes (Ranked)

Most common (~75%)

Dirty flame sensor

What: Coating prevents reliable flame detection.

How to check: Pull and inspect for buildup.

Fix: Clean with emery cloth.

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Common

Low gas pressure

What: Inconsistent gas pressure causes flame instability.

How to check: Tech measures manifold pressure.

Fix: Adjust or call utility.

Less common

Bad gas valve

What: Valve doesn't deliver steady gas flow.

How to check: Tech test.

Fix: Replace valve.

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Diagnostic Steps

Reset furnace by cutting power
Pull and clean flame sensor
Watch heat cycle
Call tech if persistent

Frequently Asked Questions

How urgent is Lennox 8 flashes?

Not critical. Often resolves with flame sensor cleaning.

DIY fix?

Yes — flame sensor cleaning is 5-minute job.

Same on Ducane?

Yes.

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Need More Help?

Try our interactive symptom diagnostic tool or browse Lennox parts.

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