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Error code reference

LG Microwave Error Code Ot

Cooling Fan Motor PCB temperature sensor short-circuit / over-temperature error.

LG codesLG microwave codes

Cooling Fan Motor PCB temperature sensor short-circuit / over-temperature error.

First step from the service manual

Repair the short circuit on temperature sensor of PCB.

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

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  • Wiring diagram references and connector pinouts from the OEM service manual
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What Ot means on a LG microwave

The Ot error code on an LG microwave indicates a short-circuit or over-temperature condition detected by the PCB-mounted temperature sensor associated with the cooling fan motor circuit. This onboard sensor continuously monitors the temperature of the control board and surrounding components during operation. When the sensor detects a temperature that exceeds the safe threshold, or when it detects a short circuit within its own sensing circuit, the microwave halts operation and displays Ot to prevent thermal damage to the electronics.

The cooling fan plays a critical role in maintaining safe operating temperatures inside the microwave. If the fan motor fails, runs slowly, or is obstructed, heat builds up around the PCB and can trigger the over-temperature condition. Separately, a short circuit in the sensor's wiring or within the sensor component itself on the board can cause a false or real fault reading, triggering the same error even if actual temperatures are within range.

Diagnosing this error begins with inspecting the temperature sensor circuit on the PCB for visible signs of a short circuit, such as burned traces, solder bridges, or damaged components. The cooling fan motor should also be checked for proper rotation and airflow. If the sensor itself is shorted on the board, the PCB may require repair or replacement. Resolving the root cause, whether it is a failed fan, blocked ventilation, or a shorted sensor circuit, is necessary before the microwave will resume normal operation.

Source: manufacturer service documentation.

Common causes of Ot

  1. 01

    Short circuit in PCB temperature sensor

    Part replacement

    The temperature sensor component on the control board may have developed an internal short circuit, causing the microwave to read an invalid or out-of-range signal. Inspect the PCB for burned traces, solder bridges near the sensor, or visibly damaged components.

  2. 02

    Cooling fan motor failure

    Part replacement

    If the cooling fan motor has seized or is running below rated speed, heat accumulates around the PCB and can drive the sensor reading above the safe threshold. Check that the fan spins freely and operates during microwave use.

  3. 03

    Blocked ventilation or airflow obstruction

    Wiring / connection

    Debris, grease buildup, or improper installation blocking the vents can cause heat to accumulate even when the fan is functional. Inspect all intake and exhaust vents for obstructions and clean if necessary.

  4. 04

    Damaged sensor wiring or connector

    Wiring / connection

    The wiring harness connecting the temperature sensor circuit to the main PCB may have chafed insulation or a loose connector causing a short. Inspect the wiring and connectors for visible damage or poor contact.

  5. 05

    Failed or damaged PCB

    Part replacement

    If the sensor circuit on the control board is irreparably shorted due to a power surge or overheating event, the board itself may need to be replaced. This is typically confirmed after ruling out the fan, wiring, and ventilation as causes.

See the test procedure for each cause

Frequently asked questions about Ot

What does Ot mean on a LG microwave?
The Ot error code on an LG microwave indicates that the temperature sensor located on the PCB, associated with the cooling fan motor circuit, has detected either a short circuit or an over-temperature condition. The microwave shuts down automatically to protect its internal electronics from heat damage. The root cause can be a faulty sensor, a failed cooling fan, blocked ventilation, or a damaged control board.
Can I fix the Ot error on my LG microwave myself?
Some causes of the Ot error, such as clearing a blocked vent or checking that the fan is not physically obstructed, can be addressed without special tools. However, repairing a short circuit on the PCB temperature sensor circuit requires electronics knowledge and is best handled by a qualified technician. Working inside a microwave carries serious risk of electric shock due to high-voltage capacitors that can retain a charge even when unplugged.
Is it safe to use my LG microwave while the Ot error is displayed?
No. The Ot error indicates an over-temperature or short-circuit condition that has caused the microwave to disable itself as a protective measure. Attempting to bypass or ignore this error and continue using the appliance could result in further damage to the control board or create a fire hazard. The underlying fault should be resolved before resuming use.
Will resetting my LG microwave clear the Ot error code?
Unplugging the microwave for a few minutes and reconnecting power may temporarily clear the Ot error, but if the underlying cause, such as a shorted sensor or a failed cooling fan, has not been corrected, the error will return. A reset does not repair the fault. Persistent or recurring Ot errors require hands-on diagnosis and repair.
How much does it cost to repair an LG microwave with an Ot error?
Repair costs vary depending on the root cause. Clearing a ventilation blockage or replacing a cooling fan motor typically costs less than replacing the main control board. In general, fan motor replacements may range from $50 to $150 in parts and labor, while PCB repair or replacement can range from $100 to $300 or more depending on the model and technician rates. If repair costs approach the price of a new unit, replacement may be worth considering.

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