American Standard Furnace Error Codes - Complete Guide

American Standard furnaces are manufactured by Trane and use identical control boards. Both brands use a single-digit LED flash code system. Count the red LED flashes between pauses. Also covers Trane.

All American Standard Error Codes

2 flashes

Trane Furnace 2 Flashes — Lockout on Retries

Locked out after exhausting ignition retry attempts.

3 flashes

Trane Furnace 3 Flashes — Pressure Switch Error

Pressure switch fault — vent, inducer, or switch problem.

4 flashes

Trane Furnace 4 Flashes — Open Limit Switch

Open limit switch — overheating. Usually restricted airflow.

5 flashes

Trane Furnace 5 Flashes — Flame Sensed With Gas Valve Off

Flame detected when gas valve should be closed — leaky valve.

6 flashes

Trane Furnace 6 Flashes — Line Voltage Polarity Incorrect

Line voltage polarity incorrect — wiring or transformer fault.

7 flashes

Trane Furnace 7 Flashes — Gas Valve Circuit Problem

Gas valve circuit problem — wiring, coil, or board fault.

8 flashes

Trane Furnace 8 Flashes — Low Flame Sensor Signal

Weak flame sensor signal — usually a dirty sensor.

9 flashes

Trane Furnace 9 Flashes — Igniter Problem

Igniter fault — usually a failed hot surface igniter.

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American Standard Furnace Error Codes - Complete Guide

All American Standard Error Codes

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