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Error code reference

LG Microwave Error Code E02

Thermistor open

LG codesLG microwave codes

Thermistor open — thermistor circuit fault detected by the P.C.B. (thermistor is open-circuited), or heater fault.

First step from the service manual

Check the connection between the thermistor and the P.C.B. assembly.

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

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What E02 means on a LG microwave

The E02 error code on an LG microwave indicates that the PCB (printed circuit board) has detected an open-circuit condition in the thermistor circuit. The thermistor is a temperature-sensitive resistor responsible for monitoring cavity or component temperatures during microwave and convection/grill operation. When the PCB reads the thermistor circuit as open, it means the signal line is broken or absent, which the control board interprets as a potentially dangerous or undefined temperature state. This triggers E02 as a protective fault.

An open thermistor circuit can result from a physically failed thermistor whose internal resistance element has broken, a disconnected or corroded wiring harness connector between the thermistor and the PCB, or damaged wiring along the signal path. Because the error code also references a possible heater fault, the PCB may flag E02 when heater-related temperature feedback is absent or out of range, suggesting the thermistor and heater subsystem share a monitoring relationship on certain LG models.

The first diagnostic step is to inspect the connector between the thermistor and the PCB assembly. A loose, burnt, or corroded connector pin can mimic a failed thermistor entirely. If the connection is secure, the thermistor itself should be tested for continuity and resistance. A completely open reading (infinite resistance) confirms the thermistor has failed internally. If wiring and the thermistor both test good, attention should shift to the PCB, which may be misreading the signal.

Source: manufacturer service documentation.

Common causes of E02

  1. 01

    Loose or disconnected thermistor connector

    Wiring / connection

    The wiring harness connector between the thermistor and the PCB can work loose over time due to vibration or thermal cycling. Inspect the connector at both ends for secure seating and any signs of corrosion or burnt pins.

  2. 02

    Failed thermistor (open circuit)

    Part replacement

    The thermistor's internal resistive element can break, resulting in infinite resistance across its terminals. Testing with a multimeter for continuity will confirm this failure, as an open-circuited thermistor will show no continuity at all.

  3. 03

    Damaged wiring between thermistor and PCB

    Part replacement

    Wire insulation can become brittle or wires can be pinched or burnt inside the microwave cavity area, breaking the signal path. Visually trace the wiring harness from the thermistor to the PCB looking for cuts, burn marks, or chafing.

  4. 04

    Heater component fault

    Part replacement

    On models where the heater and thermistor circuits share monitoring through the PCB, a heater failure can trigger E02 alongside or instead of a direct thermistor fault. Inspect the heater element for visible damage or open-circuit readings.

  5. 05

    Faulty PCB assembly

    Part replacement

    If the thermistor, its wiring, and all connectors test correctly, the PCB itself may be misreading the thermistor signal due to a failed input circuit. PCB replacement is typically a last-resort diagnosis after all other components are ruled out.

See the test procedure for each cause

Frequently asked questions about E02

What does E02 mean on a LG microwave?
E02 on an LG microwave indicates a thermistor open-circuit fault detected by the PCB. The control board is not receiving a valid signal from the thermistor, which monitors internal temperatures during operation. This can result from a disconnected connector, a failed thermistor, damaged wiring, or in some cases a heater fault. The microwave will not operate normally until the fault is resolved.
Can I fix an E02 error on my LG microwave myself?
Checking and reseating the connector between the thermistor and the PCB is a straightforward first step that a confident DIYer can perform after unplugging the unit. Testing the thermistor with a multimeter for continuity is also within reach for someone comfortable with basic electrical testing. However, working inside a microwave carries serious safety risks due to high-voltage capacitors that retain charge even when unplugged, so caution and proper discharge procedures are essential. If the PCB itself needs replacement, professional repair is recommended.
Is it safe to use my LG microwave while E02 is displayed?
No, you should not continue using the microwave while E02 is active. The thermistor is a safety-critical component that allows the PCB to monitor and control operating temperatures. Running the unit without reliable temperature feedback could result in overheating, damage to internal components, or a fire hazard. Discontinue use until the fault is diagnosed and repaired.
Will resetting my LG microwave clear the E02 error?
A power reset by unplugging the microwave for several minutes may temporarily clear the E02 display, but the error will return if the underlying fault is still present. Because E02 reflects an actual circuit or component condition detected by the PCB, clearing the code without repairing the cause does not resolve the problem. A proper repair of the thermistor circuit or related components is required for a lasting fix.
How much does it cost to repair an LG microwave E02 error?
Repair costs vary depending on which component has failed. A replacement thermistor is generally an inexpensive part, typically in the range of $10 to $30, while a PCB assembly can cost considerably more, often between $80 and $200 or higher depending on the model. Adding professional labor charges, a full repair could range from $100 to $300 or more. In some cases, particularly with older or lower-cost models, replacement of the entire unit may be more economical than PCB repair.

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