Look up your error code
Type the brand and code (e.g. Carrier code 33, Goodman 3 flashes) or describe what the unit is doing. We match it against every documented fix — instantly, in your browser.
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Browse error code charts
Every code we've documented, grouped by brand and equipment. Each chart lists what the code means and how urgent it is.
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CarrierGoodmanTraneLennoxYorkRheemBryantAmanaHoneywellAmerican Standard
How to read a flashing furnace light
Most furnaces report faults through an LED on the control board, visible through a small window in the lower door. Carrier, Bryant and Lennox boards blink a two-digit code (three short flashes, a pause, then one flash is code 31). Goodman, Amana, Trane, American Standard and York boards repeat a single count (three flashes, a long pause, three flashes). Count the pattern twice before you open the door: removing the door cuts power and clears the code on many boards. Some newer units show the code on the thermostat instead.