Frigidaire Dishwasher Sensor Replacement Guide

Two sensors, two functions#

The DishSense soil sensor sits in the sump housing below the flat mesh filter. It measures water turbidity — how cloudy the wash water is — using a light emitter and a detector. As water circulates, the sensor gauges how much food contamination remains, and the control board extends or shortens the wash based on that reading. Only Gallery and Professional models include DishSense; standard models do not.

The NTC thermistor handles temperature. Its resistance changes with heat, and the board reads it to manage water heating and cycle timing. A healthy thermistor reads in a predictable range for a given temperature — on the order of 10,000 to 15,000 ohms at room temperature near 68°F, or 20°C, and much lower when hot.

Symptoms by sensor#

• Cycles finish too fast and dishes stay dirty — the DishSense sensor reads falsely clean.
• Cycles drag on toward 3 hours — the DishSense reads falsely dirty, or the NTC keeps the board waiting for heat.
• No heat or scalding water — an NTC thermistor feeding the board a wrong temperature.
• Erratic cycle length on a Gallery model — a soil sensor fouled by film on its optical window.

Testing the sensors#

A meter settles the NTC quickly. The DishSense is harder to test directly, so start by cleaning its window, since a greasy film over the optics is a frequent cause of soil-sensing errors that looks exactly like a dead sensor.

Replacing a sensor#

1. Disconnect power and shut the water as a precaution.
2. For the DishSense, remove the lower rack, spray arm, and filter to reach the sump housing; for the NTC, access its mount per your model.
3. Disconnect the wiring and release the sensor from its housing.
4. Fit the replacement, reconnect, and reassemble the sump components.
5. Restore power and run a cycle to confirm correct heating and timing.

Avoid the common misdiagnosis#

The mistake to avoid is replacing the DishSense soil sensor when the real problem is a dirty optical window or a clogged filter. Both starve the sensor of a clean reading and produce short or endless cycles, and both cost nothing but a wipe-down to rule out. Clean the sump, the fine filter, and the sensor window first, run a cycle, and only order a sensor if the erratic behavior survives a genuinely clean machine. When you do replace the NTC, confirm the resistance of the new part against the expected range before trusting it, so a defective replacement does not send you chasing the same symptom twice.

Sensor life and water quality#

Both Frigidaire dishwasher sensors are long-lived parts, and the biggest factor in how long they last is water quality. Hard-water scale coats the NTC thermistor and films over the DishSense optical window, and in both cases the sensor keeps working but reads progressively less accurately until the board's decisions go wrong. Periodic descaling and keeping the sump and filter clean therefore do more to preserve sensing accuracy than anything else. If your dishwasher has drifted toward erratic cycle lengths over months rather than failing suddenly, suspect film and scale before a dead sensor, and run a cleaning cycle with a descaler first. When you do replace a sensor, seat its connector firmly and check for corrosion at the terminals, since a resistive connection at the plug produces the same wrong readings as a failed sensor and is far cheaper to fix.

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