LOW URGENCY

Trane Furnace 8 Flashes — Low Flame Sensor Signal

8 flashes

Weak flame sensor signal — usually a dirty sensor.

Brand: Trane (Also covers American Standard) | Equipment: Gas Furnace

What This Code Means

8 flashes means the flame sensor is detecting flame, but the signal is weaker than expected. Common pre-failure warning before code 2 lockout.

Likely Causes (Ranked)

Most common (~80%)

Dirty flame sensor

What: Carbon buildup or oxide layer weakens the signal.

How to check: Pull sensor; check for any coating.

Fix: Clean with fine emery cloth.

Shop parts

Common

Weak igniter affecting flame quality

What: Slow ignition produces unsteady initial flame.

How to check: Watch igniter glow brightness.

Fix: Replace igniter.

Shop parts

Less common

Gas pressure problem

What: Low gas pressure produces weak flame.

How to check: Tech measures manifold pressure.

Fix: Adjust regulator or call gas utility.

Diagnostic Steps

Pull and clean flame sensor
Watch heat cycle — note flame quality
Replace igniter if glow is weak
Call tech for pressure issues

Frequently Asked Questions

Is Trane 8 flashes urgent?

Not critical, but address soon — weak signal often progresses to full ignition lockout.

How to clean Trane flame sensor?

Cut power, pull sensor (one screw), wipe rod with fine emery cloth or steel wool, reinstall.

Same on American Standard?

Yes — same code, same procedure.

Related Trane Codes

Related Symptoms

Need More Help?

Try our interactive symptom diagnostic tool or browse Trane parts.

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