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Error code reference

LG Refrigerator Error Code 25E

FZ-DEF Heater Error

LG codesLG refrigerator codes

FZ-DEF Heater Error — freezer defrost heater housing separation, contact error, disconnection, short circuit, or temperature fuse error; defrost did not finish after 80 minutes of continuous heating.

First step from the service manual

Disconnect Main PCB CN70 wire; measure resistance between CN70 Brown and CN70 Gray — should be 63 (230) ohm ±7%. 0 ohm = heater short, infinity = wire/bimetal open.

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

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What 25E means on a LG refrigerator

The 25E error code on an LG refrigerator indicates a freezer defrost heater fault, specifically logged when the defrost cycle fails to complete within 80 minutes of continuous heater operation. The freezer defrost system relies on a resistive heating element to melt accumulated frost off the evaporator coils. When the control board detects that the heater has been running for 80 minutes without the defrost termination condition being met, it flags this error and records the failure. The fault can originate from several points in the circuit: a physical separation of the heater housing, a poor or broken electrical contact, a complete wire disconnection, a short circuit within the heater element itself, or an open thermal fuse (bimetal limiter) that has tripped and interrupted the circuit.

Diagnosis begins at the Main PCB connector CN70. With the CN70 wire harness disconnected, technicians measure resistance between the Brown and Gray wires on that connector. A healthy defrost heater circuit should read approximately 63 ohms for 230-volt models, with an acceptable tolerance of plus or minus 7%. A reading of 0 ohms indicates a direct short within the heater element. A reading of infinite resistance (open loop) points to a broken wire, a failed bimetal thermal fuse, or a physically disconnected heater housing. Both conditions prevent proper defrost operation and will trigger the 25E code.

If the resistance falls within spec but the error persists, the fault may lie with the Main PCB itself failing to properly energize the heater circuit. Additionally, a correctly functioning heater that still cannot complete defrost within 80 minutes may indicate an unusually heavy frost load caused by a door seal failure, excessive door openings, or a prior long-term defrost system problem that allowed ice to build up beyond what one cycle can clear.

Source: manufacturer service documentation.

Common causes of 25E

  1. 01

    Open thermal fuse (bimetal limiter)

    Part replacement

    The bimetal thermal fuse is a one-time safety device that opens permanently if it overheats. A tripped bimetal reads as infinite resistance between the CN70 Brown and Gray wires and is one of the most frequent causes of defrost circuit failures.

  2. 02

    Defrost heater open circuit or disconnection

    Part replacement

    The heater element itself can burn out or physically disconnect from its housing contacts, resulting in an infinite resistance reading at CN70. Inspect the heater and its connector terminals for visible damage, corrosion, or separation.

  3. 03

    Defrost heater short circuit

    Part replacement

    A shorted heater element causes the resistance between CN70 Brown and Gray to read 0 ohms instead of the expected 63 ohms (plus or minus 7%). This typically requires heater replacement and may also warrant inspection of the wiring harness for damage.

  4. 04

    Wiring harness damage or poor contact

    Wiring / connection

    Corrosion, pinching, or physical damage along the harness between the Main PCB and the heater assembly can create intermittent or complete open circuits. Check the CN70 connector pins and the full wire run for continuity and secure seating.

  5. 05

    Main PCB failure

    Part replacement

    If the heater, thermal fuse, and wiring all test within specification but the error persists, the Main PCB may not be properly supplying voltage to the CN70 circuit during the defrost cycle. Board replacement is the corrective action in this scenario.

See the test procedure for each cause

Frequently asked questions about 25E

What does 25E mean on a LG refrigerator?
The 25E code means the freezer defrost heater circuit has a detected fault. Specifically, the refrigerator's control board logged the error because the defrost cycle did not finish within 80 minutes of continuous heater operation. The root cause can be a failed heater element, an open thermal fuse, a short circuit, broken wiring, or poor connector contact at the heater housing.
Can I fix a 25E error myself, or do I need a technician?
A knowledgeable DIYer comfortable with basic electrical testing can diagnose this error by disconnecting the CN70 connector on the Main PCB and measuring resistance between the Brown and Gray wires with a multimeter. A reading of 0 ohms or infinite resistance pinpoints the fault to the heater circuit. Replacing a thermal fuse or heater element is within reach for many DIYers, but working with refrigerator wiring does require care and some comfort with disassembly.
Is a 25E error on my LG refrigerator a safety hazard?
The 25E code itself is not an immediate safety emergency, but it does mean your freezer is not defrosting properly. Over time, frost buildup will block airflow and cause temperatures to rise in both the freezer and refrigerator compartments, putting food safety at risk. It is advisable to address the fault promptly rather than leaving it unresolved.
How much does it cost to repair a 25E error on an LG refrigerator?
Repair cost depends on which component has failed. A replacement thermal fuse or bimetal limiter is typically an inexpensive part, with DIY repair costs ranging from roughly $10 to $30 in parts. A defrost heater element replacement generally falls in the $20 to $60 range for the part. If the Main PCB requires replacement, costs rise significantly, often falling between $150 and $350 for the part alone, plus labor if a technician is involved.
Will resetting my LG refrigerator clear the 25E error code?
A power reset may temporarily clear the 25E code from the display, but it will not resolve the underlying electrical fault in the defrost heater circuit. If the heater, thermal fuse, or wiring has failed, the defrost cycle will fail again and the code will return. The fault must be diagnosed and the defective component repaired or replaced for the error to clear permanently.

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