LG Dishwasher Sensor Replacement

Symptom, Sensor, and Code#

All three are inexpensive parts, so the diagnostic time is worth more than the components; exact pricing varies by model.

What Each Sensor Does#

The thermistor is an NTC resistor near the flow-through heater below the tub; it reports water temperature so the board can hold the wash at the right heat. The turbidity sensor is an optical soil reader in the sump that measures how dirty the recirculating water is, letting the board stretch or shorten a cycle. The water-level sensor is a pressure switch that senses tub water through an air tube — overfill and underfill both trace back to it.

Testing the Thermistor#

Disconnect power and unplug the thermistor's 2-pin connector, then meter its resistance. At room temperature, around 72F, expect roughly 50K ohms; measured hot after a cycle, near 150F, it should drop to about 5K ohms. An infinite reading means the sensor is open and zero means it is shorted — replace it with 6322FR2046A either way.

Testing the Other Two#

The turbidity sensor is optical, so a meter tells you little. Clean its window with a soft cloth and clear water first; if the long- or short-cycle symptom clears, it was only dirty, and if it persists, fit 6501KW2002A. For the water-level sensor, pull the air tube and blow gently into the port — you should hear the switch click. No click means the diaphragm is stuck or torn, and 6601ER1006E is the replacement.

Replacement by Sensor#

• Thermistor: pull the bottom kick plate, unplug the 2-pin connector, release the clip or single screw, and swap it — a two-minute job.
• Turbidity: remove the bottom panel, twist-lock or unscrew the sensor from the sump housing, and clean the sump while you are in there.
• Water level: from the bottom panel, disconnect the air tube and electrical plug and remove the one or two screws holding it to the tub wall.

You need only a Phillips #2, a small flathead, a multimeter, and a flashlight for any of the three.

Where Each Sensor Sits#

Access changes with the sensor. The thermistor and turbidity sensor both live low — the thermistor at the flow-through heater and the turbidity reader in the sump housing — so both come out from behind the bottom kick plate. The water-level pressure sensor mounts higher on the side of the tub, following its air tube up from the sump. Trace that clear air tube if you are unsure which part you are looking at: it runs from the tub to the pressure sensor and to nothing else.

Clean Before You Replace#

Two of the three parts respond to cleaning before they need replacing. Wiping the turbidity window clears most stuck-cycle complaints, and flushing the water-level air tube of trapped debris restores a sensor that only seemed dead. The thermistor is the exception — it either meters in range or it does not — so save the parts spend for the sensor a test actually condemns.

How Long Each Sensor Lasts#

Thermistors generally run 10-15 years. Turbidity sensors can last the life of the machine if kept clean, but a window permanently clouded by mineral deposits may push a swap at 8-10 years. Water-level sensors depend on a rubber diaphragm that hardens over 10-12 years. LG covers all three under the standard 1-year parts and labor warranty.

Can a Bad Sensor Harm the Dishwasher#

A failed water-level sensor is the one to fix promptly: if it lets the tub overfill, water can reach the control board. A failed thermistor can leave the heater running longer than intended, though most LG boards carry a thermal cutoff as a backstop. Neither should be ignored once you have pinned it down.