Furnace blower motor fault codes by brand

The blower is the one furnace component that reports faults in two entirely different languages: mechanical failures like a locked rotor, and communication failures that only exist because modern blowers are networked devices.

Some of the faults listed here are gas-safety faults. Those ones involve the gas valve, the burner compartment, or the heat exchanger — the parts whose failure can put combustion products, including carbon monoxide, into the air the house breathes, and each carries this warning on its own page. Do not keep resetting a furnace that reports one of them in order to hold the heat on. Have it looked at by a licensed technician, and make sure there is a working carbon monoxide alarm on every level of the home, including the level the furnace is on. The conditions that mean stop now.

What the indoor blower motor does

The indoor blower is the large fan that moves house air across the outside of the heat exchanger and out through the ducts. It is not the inducer: the inducer moves combustion gas through the inside of the heat exchanger and out of the flue, and the two are separate motors with separate faults. The blower starts after the burners have been alight for a short delay, so that the first air out of the registers is warm rather than cold, and it runs on after the burners stop to carry the remaining heat out of the exchanger.

Why one part produces several different codes

On an older furnace the blower is a simple motor on a relay, and its codes are mechanical: it is not turning, it is drawing too much current, its rotor is locked. On a variable-speed furnace the blower is an electronically commutated motor with its own controller, and the board talks to it over a serial link — which is why several manufacturers publish codes for a blower that will not answer, a blower whose horsepower does not match what the board expects, and a blower reporting its own overheating. Those codes describe a conversation failing, not a fan failing, and a motor that is mechanically perfect can produce every one of them. The other direction is worth knowing too: a blower that is not moving air often reports as a limit code rather than a blower code, because heat builds up in the exchanger until the high limit opens. Two of the codes below say exactly that.

Every indoor blower motor code on this site

16 codes across 6 control families. The meaning is the manufacturer's, from the document listed at the foot of each code page.

Brand	Code	What it reports
Carrier	Status code 12	Blower running after power up
Goodman	b0	Blower motor is not running
Goodman	b1	Blower communication error
Goodman	b2	Blower motor horsepower mismatch
Goodman	b3	Blower motor operating at a power, temperature, or speed limit
Goodman	b4	Blower motor current trip or lost rotor
Goodman	b5	Blower motor locked rotor
Goodman	b6	Blower motor over or under voltage trip, or over temperature trip
Goodman	11 red flashes	Limit switch open due to blower failure
Lennox	Alert code 201	Indoor blower motor communication lost
Lennox	Alert code 202	Blower motor and unit size mismatch
Lennox	Alert code 292	Indoor blower motor will not start — Watchguard
Lennox	Alert code 295	Indoor blower motor overheating
Trane	E17	Blower motor not responding to communication
Trane	E18	Blower communication failure on the control
York	11 red flashes	Limit switch open more than five minutes — blower failure

Before you work on it

The blower is what carries heat away from the heat exchanger. A furnace that keeps tripping its high limit because the blower is not moving enough air is overheating the exchanger every time it runs, and repeated overheating is one of the things that cracks one. Airflow faults are worth fixing promptly rather than resetting around.

Other parts

Sources

Every code meaning above comes from the manufacturer document behind its code page:

This site is a reference, not a substitute for a licensed HVAC technician. Gas appliances can leak carbon monoxide and cause fire. Anything involving gas lines, the heat exchanger, or the flame sensing circuit should be handled by a licensed professional. Pages are written with AI assistance from the sources listed on each page and checked against them before publishing.