LG Dishwasher Turbidity Sensor Replacement — What This Part Does
The turbidity sensor is an optical sensor mounted in the sump that measures how dirty the circulating wash water is during the cycle. It reads cloudiness and soil level so the control board can decide whether to extend washing, add extra rinses, or finish the cycle. LG sells this component as a standalone turbidity sensor on some models (such as part ABQ75742401) and as an integrated sensor assembly on others (such as part 6501DD2001A).
Most turbidity problems start with food film, grease, or scale coating the sensor window and blocking the optical path. If the sensor signal becomes implausible or drops out completely, the dishwasher may over-wash, under-wash, repeat rinses endlessly, or stop mid-cycle with a sensor-related fault code. Failed sensor electronics or harness connector corrosion are also possible once the sensor window has been ruled out.
Signs It Needs Replacing
- Dishes still dirty after a full cycle The sensor fails to detect soil level accurately, so the control ends the wash too early or skips needed rinses.
- Cycle repeats rinses or runs much longer than normal A contaminated sensor constantly reports dirty water, causing the control to add rinses or extend wash time indefinitely.
- Sensor fault code displayed on the control panel The dishwasher stops mid-cycle and shows a service code tied to the water or soil-sensing circuit, depending on your model.
- Cycle behavior changes unpredictably between runs Intermittent sensor readings cause the control to vary wash time and rinse count from one load to the next without pattern.
- Water remains murky or soapy after final drain The sensor misreads water quality and allows the cycle to finish without clearing all detergent or soil from the tub.
- Clean dishes get rewashed or cycle restarts on its own Erratic sensor signals make the control think water is still dirty, triggering automatic rewash or cycle extension.
How to Replace It
- Unplug the dishwasher from the wall outlet or switch off the dedicated circuit breaker at the panel.
- Turn off the water supply valve under the sink or at the wall stub-out feeding the dishwasher fill line.
- Remove the lower kick panel or base access cover by pulling the panel forward or removing the retaining screws, depending on your model.
- Locate the turbidity sensor or sensor assembly at the bottom of the sump (typically a small module with a wiring harness attached near the filter area).
- Inspect the sensor window and surrounding sump passage for food film, grease, or mineral scale, and clean any deposits with a soft damp cloth and fresh water.
- Disconnect the sensor wiring harness by pressing the locking tab and pulling the connector straight off the sensor terminals.
- Remove the old turbidity sensor or sensor assembly by turning it counterclockwise or releasing the mounting clip, then lifting it out of the sump.
- Install the new sensor by inserting it into the sump mount and turning clockwise (or snapping the clip) until it seats fully and the alignment marks line up.
- Reconnect the wiring harness to the new sensor, making sure the locking tab clicks and the connector is fully seated.
- Replace the lower access panel or kick plate, restore water and electrical power, and run a short rinse cycle to check for leaks and confirm normal operation.
The Part You Need
| Part | Notes |
|---|---|
| LG dishwasher turbidity sensor or sensor assembly | Amazon | Part number varies by model (examples: ABQ75742401, 6501DD2001A). Find your exact part by checking the model and serial plate inside the door frame and cross-referencing with the LG parts breakdown for your dishwasher. |
Related Error Codes
If this part is failing you may also see one of these codes:
- Lg Dishwasher Ae error code
- Lg Dishwasher Be error code
- Lg Dishwasher Ce error code
- Lg Dishwasher Cr error code
- Lg Dishwasher E1 error code
- Lg Dishwasher Fe error code
- Lg Dishwasher He error code
- Lg Dishwasher Ie error code
- Lg Dishwasher Le error code
- Lg Dishwasher Ne error code
When to Call a Pro
If you are uncomfortable working around electrical connectors in the wet sump area, or if the dishwasher continues to show sensor faults or abnormal cycle behavior after you have cleaned the sensor window and checked the harness connection, call a qualified appliance technician. Multiple sensors (turbidity, thermistor, water level) share the same sump space, and misidentifying the failed component or damaging the wiring harness during replacement can lead to new faults or water leaks that cost more to fix than the original problem.