On Goodman and Amana variable-speed furnaces such as the GMVC96, AMVC96 and modulating GMVM models, the dual 7-segment display shows fault codes, and every code that starts with a lowercase b points at the circulator blower motor or its airflow. The E-codes cover ignition, pressure switch, limit and wiring faults. Read the blower codes first, because they decide whether you are buying a motor or chasing a duct problem.
Key Takeaways
- b0 through b9 are circulator blower codes: not running, communication loss, motor mismatch, limiting, trips, locked rotor, voltage and low airflow.
- b2 (motor mismatch) usually follows a wrong-horsepower replacement or a bad shared data set, not a failed motor.
- b3, b4 and b9 are airflow problems far more often than motor failures: check filters and ductwork first.
- E0 is ignition lockout, and it resets after one hour or with a power or thermostat cycle if the cause is gone.
- Always confirm against the troubleshooting chart for your exact model, since display revisions differ.
How Goodman, Amana and Daikin Furnaces Show Codes
Goodman and Amana furnaces are built by Daikin Comfort Technologies, and one installation manual covers both brands. Two-stage and modulating models use a dual 7-segment display on the integrated control module, and ComfortNet thermostats may show a matching "Check Furnace" message. Older single-stage boards use a single LED that flashes a count; on those, Goodman service literature confirms 6 flashes as a tripped rollout switch or open control board fuse. Because flash legends vary by board, use the label inside the blower door for the other counts. Daikin-branded furnaces should also be checked against the unit's own chart.
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Blower Codes First
b0: Motor Not Running
The circulator blower is not running when it should be. Check wiring at the motor power leads, then inductor continuity on 3/4 HP and 1 HP models. Yes, a failed motor is a leading cause.
b1: Motor Communication Lost
The control has lost communication with the motor. Check the motor control lead connections, then the motor and the control module. The motor is a common cause, but a loose control harness is the five-minute check.
b2: Motor Mismatch
The horsepower in the shared data set does not match the installed motor. Compare the motor nameplate horsepower with the furnace model, and verify the shared data set (memory card). This code is the usual result of installing the wrong horsepower, so match the OEM part number when ordering.
b3: Motor Limits
The motor is running at a power, temperature or speed limit. Causes are blocked filters, restrictive ductwork and high ambient temperature. The motor is rarely the cause.
b4: Motor Trips
The motor senses a loss of rotor control or high current. Check filters, grilles, registers and the furnace air inlet and outlet for blockage. Heavy loading is the common cause, so inspect airflow before the motor.
b5: Locked Rotor
The motor failed to start 10 consecutive times. Check the blower housing for obstruction, spin the wheel by hand, and look for seized bearings. A seized or failed motor is common here. The full power, signal and shaft sequence is in how to test an ECM blower motor.
b6: Motor Voltage
The motor shut down on over or under voltage, or on an over-temperature condition in its power module. Verify line voltage against the furnace rating plate. High ambient temperature also contributes.
b7: Motor Parameters
The motor lacks the information to operate, or has failed to start 40 consecutive times. Check that the control holds the correct shared data and look for a locked rotor.
b9: Low Airflow
Airflow is lower than demanded. Check filters, ductwork and registers, and confirm the ductwork is sized for the system. This is an airflow code, not a motor code.
Heating and Control Codes
| Code | Meaning | Blower Motor the Cause? |
|---|---|---|
| E0 | Lockout after 3 failed ignition attempts | No |
| E1 / E2 | Low-stage pressure switch closed at start / not closing | No |
| E3 | Primary, auxiliary or rollout limit open | Yes, via airflow or a failed motor |
| E4 | Flame sensed with no call for heat | No |
| E5 | Open fuse or low-voltage short | No |
| E6 | Weak flame signal | No |
| E7 | Igniter circuit fault | No |
| E8 / E9 | High-stage pressure switch closed / not closing | No |
| EA | 115 V AC polarity reversed or poor ground | No |
| EE (ComfortNet thermostat message only; the board display stays blank) | Internal fault: no 115 or 24 V power, blown 3 A fuse, or control failure | No |
E3: Limit Open
Goodman lists blocked filters, restrictive ductwork, improper circulator speed or a failed circulator blower motor as causes, with the circulator running continuously. Check the filter and registers, then confirm the blower reaches speed.
E0: Lockout and Reset
The control resets itself after one hour. To reset sooner, interrupt 115 V power, or lower the thermostat for 1 to 20 seconds with no call for heat and then restore it. If the cause remains, the furnace locks out again. Some newer display revisions show this lockout as EE0.
Which Motor Your Goodman or Amana Furnace Uses
Goodman and Amana OEM numbers are available on X13 constant-torque, ECM 2.3 and EON variable-speed motors, depending on model. Match the OEM part number on the motor, not the furnace model. Start at the Goodman replacement blower motors page. Wrong horsepower produces b2, so verify the nameplate before ordering.
When to Call a Pro
Call a licensed technician for E4, E7 and EA, any gas valve work, repeat lockouts, and rollout trips. The codes above are reference only, and the generic HVAC fault code lookup covers other brands. Carrier owners can use the Carrier furnace and AC error codes guide.
FAQs
What does b0 mean on a Goodman furnace?
The circulator blower motor is not running when it should be. Check the motor power leads, the inductor on 3/4 HP and 1 HP models, then the motor itself.
What does the b2 code mean?
The horsepower in the control's shared data does not match the installed motor. It usually follows a wrong-horsepower replacement or a wrong memory card.
How do I reset a Goodman furnace lockout?
Wait one hour for the automatic reset, interrupt 115 V power to the furnace, or cycle the thermostat off for 1 to 20 seconds. If the cause still exists, the lockout returns.
Are b3, b4 and b9 codes caused by a bad motor?
Seldom. They indicate limiting, heavy loading or low airflow, so inspect filters, registers and ductwork first.
Do Amana furnaces use the same codes as Goodman?
The installation manual covers both brands with the same troubleshooting chart. Daikin-branded models should be checked against their own chart.
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