GE Refrigerator Error Code B

Error code B on a GE refrigerator indicates a failed thermistor amplifier circuit on the main control board. During its self-diagnostic routine, the control board runs a thermistor test and evaluates the signal through the onboard amplifier stage. When that amplifier returns an invalid or out-of-range result, the board logs code B and flags itself as the faulty component. The thermistor sensor itself may be functioning correctly; the failure is in the board's ability to read and process the signal.

For homeowners, the thermistor is a small temperature sensor inside the refrigerator that tells the control board how cold the compartment is. The main control board is the electronic brain of the refrigerator. In this case, a circuit on that board responsible for interpreting the thermistor's signal has failed. Because the board can no longer accurately read temperatures, it cannot regulate cooling properly, which means your refrigerator may stop maintaining safe food temperatures.

Code B is hardware-specific to the main control board's internal amplifier and is not triggered by wiring faults or a bad thermistor alone. GE's diagnostic system isolates the amplifier failure to the board itself, which is why board replacement is the first and primary repair step.