American Standard Furnace error codes
8 American Standard furnace codes and problems, each with ranked causes, safe homeowner checks and honest repair costs. Count the flashes or read the code on your control board, then find it below. Legends vary by board revision, so confirm against the label inside your unit's door. Trane uses the same control boards — see Trane furnace codes.
| Code | What it means | Severity |
|---|---|---|
| 2 flashes | American Standard furnace 2 flashes means an ignition-retry lockout that auto-resets in 1 hour. See causes, safe checks, and repair costs from $0 to $1,200. | Call a pro |
| 3 flashes | American Standard furnace 3 flashes means a pressure switch fault. Common causes, safe checks, technician diagnosis, and repair costs from $0 to about $1,200. | Call a pro |
| 4 flashes | 4 flashes means an open high-limit or rollout switch from restricted airflow or overheating. Causes, safe checks, fixes and $0–$3,500 costs. | Call a pro |
| 5 flashes | American Standard furnace 5 flashes means flame sensed with the gas valve off. Causes, safe checks, and repair costs from $0 to $700+. | Call a pro |
| 6 flashes | American Standard furnace 6 flashes means reversed 115 VAC polarity or poor grounding. Causes, safe checks, and repair costs from $0 DIY to $350. | Call a pro |
| 7 flashes | American Standard furnace 7 flashes means a gas valve circuit error. Causes, safe checks, and repair costs from $0 DIY to $1,200+ pro. | Call a pro |
| 8 flashes | American Standard furnace 8 flashes means a weak flame-sense signal from a dirty sensor. Causes, safe checks and repair costs from $0 DIY to $250. | Call a pro |
| 9 flashes | American Standard furnace 9 flashes means an open igniter circuit or low current draw. Causes, safe checks, and repair costs ($0 DIY–$350). | Call a pro |
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