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Error code reference

LG Refrigerator Error Code E 21

Freezer fan error (RSG5B* model display).

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Freezer fan error (RSG5B* model display).

First step from the service manual

Check voltage between MAIN PCB CN74 GRAY and BLUE; should be 7V~12V.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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What E 21 means on a LG refrigerator

The E 21 error code on LG RSG5B* series refrigerators indicates a freezer evaporator fan fault. The freezer fan is responsible for circulating cold air from the evaporator coil throughout the freezer and, in many configurations, into the fresh food compartment. When the main PCB detects an abnormal signal from the fan motor circuit, it logs this fault and displays E 21 on the control panel. The fan motor relies on a regulated DC voltage supplied directly from the main PCB to spin at the correct speed and direction.

The first diagnostic step is to measure the voltage between the MAIN PCB connector CN74 GRAY wire and the BLUE wire. This supply voltage should read between 7V and 12V under normal operating conditions. If the voltage falls outside this range, the fault likely originates at the main PCB or the wiring harness rather than the fan motor itself. If the voltage is within specification but the fan still does not operate, the fan motor assembly is the more probable failed component. Technicians should also inspect the connector at CN74 for corrosion, bent pins, or loose seating before condemning either component.

Common root causes include a seized or open-circuit fan motor, ice buildup around the fan blade restricting rotation, damaged wiring between the PCB and the motor, a faulty fan motor hall sensor, or a defective main PCB failing to deliver proper output voltage. Because the freezer fan is critical to maintaining target temperatures, an active E 21 fault will typically result in rising freezer temperatures and potential food spoilage if not addressed promptly.

Source: manufacturer service documentation.

Common causes of E 21

  1. 01

    Failed freezer fan motor

    Part replacement

    The fan motor itself may have a seized bearing, open winding, or failed internal hall sensor. If CN74 voltage is within the 7V to 12V specification but the fan does not spin, the motor assembly is the likely culprit.

  2. 02

    Ice buildup blocking the fan blade

    Wiring / connection

    Excess frost accumulation around the evaporator can lock the fan blade in place, causing the motor to stall and trigger the error. Manually defrosting the freezer and checking for blade obstruction is a low-cost first step.

  3. 03

    Damaged or disconnected wiring harness

    Wiring / connection

    The wiring between CN74 on the main PCB and the fan motor can suffer from chafing, a loose connector, or broken conductors. Inspect the harness and the CN74 connector pins for corrosion or poor contact.

  4. 04

    Defective main PCB

    Part replacement

    If the voltage at CN74 between the GRAY and BLUE wires measures outside the 7V to 12V range despite correct line voltage to the board, the main PCB may not be delivering proper output to the fan circuit.

  5. 05

    Faulty fan motor hall sensor

    Part replacement

    The fan motor uses a hall effect sensor to report speed feedback to the PCB. A failed sensor can cause the board to detect no rotation signal and register E 21 even when supply voltage is correct.

See the test procedure for each cause

Frequently asked questions about E 21

What does E 21 mean on a LG refrigerator?
E 21 on an LG RSG5B* series refrigerator indicates a freezer evaporator fan error. The main PCB has detected a problem with the fan motor circuit responsible for circulating cold air through the freezer compartment. This can be caused by a failed motor, ice obstruction, wiring damage, or a fault in the main PCB output. The freezer will struggle to maintain proper temperatures while this error is active.
Can I fix the E 21 error myself?
Some causes of E 21 are DIY-friendly. You can start by unplugging the refrigerator, removing any ice buildup around the freezer fan, and checking that the fan connector is securely seated. If the fan blade spins freely by hand and connections are intact, diagnosing whether the fault is in the fan motor or the main PCB requires a multimeter to measure voltage at CN74, which is more suited to a technician.
Will resetting the refrigerator clear the E 21 error?
Unplugging the refrigerator for a few minutes may temporarily clear the display, but E 21 will return if the underlying fault is still present. A reset is useful for ruling out a one-time glitch, but if the error reappears after power is restored, the fan motor, wiring, or PCB requires further diagnosis and likely repair.
Is it safe to keep using my refrigerator while E 21 is showing?
Continuing to run the refrigerator with an active E 21 error is not recommended. Without a functioning freezer fan, cold air cannot circulate properly, and freezer temperatures will rise. This puts frozen food at risk of spoilage and can cause other components, such as the compressor, to work harder than intended. Address the fault as soon as possible.
How much does it cost to repair an E 21 error on an LG refrigerator?
Repair costs depend on the root cause. A replacement freezer fan motor typically ranges from $30 to $80 for the part, with labor adding $80 to $150 if a technician is hired. If the main PCB is faulty, part costs alone can range from $100 to $300 or more depending on availability. A service call to diagnose the exact cause is often worthwhile before purchasing parts.

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