Heil / Tempstar / Comfortmaker / KeepRite (ICP) · Furnace error code

10 flashesLine voltage polarity reversed

Cross-checked High-voltage / caution

Unlock what this code means, its causes, tests and parts

Full library + AI assistant for $34.90, one time.

OnCall Tech is a reference tool for trained technicians and can make mistakes. Always disconnect power and confirm with the manufacturer's documentation before you work.

Related diagnostic guides

Guide · Furnace

Burners light, then shut off after a few seconds (flame sensor)

The board must prove flame by flame rectification through the flame sensor. A dirty or oxidized sensor, poor ground or reversed polarity makes the board shut the gas off right after ignition.

5 steps ~30 mineasy

Guide · Furnace

Furnace won't turn on (no LED, nothing runs)

A dark board means no 120 V or no 24 V. Check the service switch, breaker, door switch, board fuse and transformer in that order.

4 steps ~30 mineasy

Guide · Furnace

Reading furnace LED flash codes by brand family (Carrier, Goodman, ICP, Rheem)

The flash code narrows the fault to one circuit before you open anything. Read it with power on, identify the board family, then use the door label to confirm. Only codes that two independent sources agree on are listed here.

8 steps ~10 mineasy