Error code reference

LG Dishwasher Error Code F-3

High temperature sensed (above 180°F); possible short circuit in thermistor circuit; dryer is inoperative.

LG codesLG dishwasher codes

High temperature sensed (above 180°F); possible short circuit in thermistor circuit; dryer is inoperative.

First step from the service manual

Check venting and check for short circuit in thermistor circuit.

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

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What F-3 means on a LG dishwasher

The F-3 error on an LG dishwasher indicates the control board has detected a temperature reading above 180°F during a cycle, or it has identified a short circuit in the thermistor circuit. The thermistor is the temperature-sensing component that feeds real-time water and air temperature data to the control board. When the board receives an out-of-range signal, either from genuinely excessive heat or from a shorted thermistor sending a false high reading, it disables the dryer function and throws the F-3 code to prevent damage. The first diagnostic step is to inspect the thermistor wiring harness for a short circuit and verify that the dishwasher's venting is not restricted.

For homeowners, the F-3 code means your dishwasher's built-in thermometer detected temperatures that are too high, or the thermometer itself has failed in a way that mimics high heat. Either way, the dishwasher has shut down its drying system as a safety measure. Your dishes may come out wet, and the wash cycle may also be affected. This is not a code you can simply reset and ignore, as the underlying cause, whether a wiring problem or a blocked vent, needs to be addressed before the appliance operates reliably again.

Source: manufacturer service documentation.

Common causes of F-3

  1. 01

    Short circuit in the thermistor circuit wiring

    Wiring / connection

    A damaged or pinched wire in the thermistor harness can create a short circuit, causing the control board to read an erroneously high temperature signal and trigger F-3 even when actual water temperature is normal. Inspecting the wiring harness for bare spots, melted insulation, or pinch points is the first diagnostic step.

  2. 02

    Failed or shorted thermistor

    Part replacement

    The thermistor itself can fail internally, producing a short circuit that sends a constant out-of-range high signal to the control board. A multimeter resistance test across the thermistor terminals will confirm whether the component has failed and needs replacement.

  3. 03

    Blocked or restricted venting

    Wiring / connection

    If the dishwasher's vent is obstructed, heat cannot escape properly during the drying cycle, causing actual temperatures inside the tub to climb above the 180°F threshold and legitimately trigger the F-3 code. Cleaning or clearing the vent assembly often resolves this without replacing any parts.

  4. 04

    Faulty control board

    Part replacement

    If the thermistor and its wiring both test within spec but the F-3 code persists, the control board itself may be misreading the thermistor signal due to a failed input circuit on the board. This is the least likely cause and should only be considered after the thermistor and wiring are confirmed good.

See the test procedure for each cause

Frequently asked questions about F-3

What does the F-3 error code mean on an LG dishwasher?
The F-3 code means the control board has detected a temperature above 180°F, or it has found a short circuit in the thermistor circuit. The thermistor is the sensor that monitors water and air temperature inside the dishwasher. Because of this fault, the dryer function is disabled. The root cause can be a wiring short, a failed thermistor, or an actual overheating condition from a blocked vent.
Is it safe to keep using my LG dishwasher when the F-3 code is showing?
Running the dishwasher with an active F-3 code is not recommended. If the code reflects a real overheating condition caused by restricted venting, continued use could cause damage to internal components or the surrounding cabinetry. If it is a false reading from a shorted thermistor or wiring fault, the drying cycle will not function correctly and the appliance is not operating as designed. Diagnose and resolve the cause before resuming normal use.
How do I fix the F-3 error code on my LG dishwasher?
Start by checking the vent for any obstruction and clearing it if blocked. Next, inspect the thermistor wiring harness for damaged insulation or a pinched wire causing a short circuit. If the wiring looks intact, use a multimeter to test the thermistor's resistance; a reading that is out of the manufacturer's specified range indicates the thermistor needs to be replaced. If both the wiring and thermistor test correctly, the control board may be at fault and should be evaluated by a technician.
How much does it cost to repair an LG dishwasher F-3 error?
If the fix is simply clearing a blocked vent, the cost is nothing beyond your time. A replacement thermistor is typically an inexpensive part, often in the $15 to $40 range, and is a manageable DIY repair for someone comfortable using a multimeter and accessing the interior of the dishwasher. If the control board is the cause, parts and labor from a technician can bring the total to $150 to $300 or more depending on your region and the specific model.
Can a short circuit in the thermistor circuit cause the F-3 code even if the dishwasher is not actually overheating?
Yes. A short circuit in the thermistor wiring or within the thermistor itself will cause the control board to receive a signal it interprets as an extremely high temperature, triggering F-3 even when the actual tub temperature is completely normal. This is why checking for a short circuit in the thermistor circuit is the first recommended step, since it is a common cause of F-3 codes that appear without any real overheating event.

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