How to Replace the Temperature Sensor (Thermistor) on a Frigidaire Dishwasher

The temperature sensor (thermistor) in a Frigidaire dishwasher monitors wash water temperature and communicates with the control board to manage cycle timing and heating element activation. On Frigidaire Gallery models, the thermistor is part of the DishSense system that also includes a soil turbidity sensor. When the temperature sensor fails, the control board cannot accurately determine water temperature, leading to the ER error code, cycles that run too long (the board keeps heating indefinitely waiting for target temp), or cycles that never activate the heater (board thinks water is already hot).

The sensor is a small probe-style thermistor located in the sump area at the bottom of the tub. It is one of the simpler replacements on a Frigidaire dishwasher since it is accessible from inside the tub without removing access panels or the dishwasher from the cabinet.

Before You Start

• Tools needed: Phillips #2 screwdriver (for kick plate access to wiring), digital multimeter, towel
• Parts needed: Temperature sensor/thermistor ($20-$45, model-specific)
• Time required: 15-25 minutes
• Difficulty: Beginner-Intermediate
• Safety warning: Disconnect power at the circuit breaker. The sensor itself is low-voltage, but it connects to the control board which operates on 120V. Never reach into the sump area while the unit has power.

Step-by-Step Instructions

Step 1: Test the Existing Sensor

Before replacing the sensor, confirm it has actually failed. The temperature sensor is a negative temperature coefficient (NTC) thermistor, meaning its resistance decreases as temperature increases.

Disconnect power at the breaker. Remove the lower access panel (kick plate, 2 Phillips screws). Locate the sensor wiring underneath the tub (usually a 2-wire connector near the sump). Disconnect the sensor wires and measure resistance with your multimeter:

• At room temperature (approximately 70-75 degrees F): expect 10,000-15,000 ohms (10-15K)
• If reading is infinite (open circuit): sensor is burned out, replace
• If reading is zero or near-zero: sensor is shorted, replace
• If reading is within range: sensor may be intermittent (test again after running hot water over it, resistance should drop noticeably)

A sensor that reads correctly at room temp but does not change with temperature exposure has failed internally and needs replacement.

Step 2: Locate the Sensor Inside the Tub

Open the dishwasher door. Remove the lower dish rack. The temperature sensor is located in the sump area at the bottom of the tub, typically near the heating element or adjacent to the filter assembly. On Frigidaire models, it is a small cylindrical probe (about 1 inch long) that protrudes into the water from the bottom of the tub or from the sump wall. It may have a small plastic retaining clip or a screw holding it in place. The sensor wire runs through the tub floor to the connector underneath.

Step 3: Remove the Old Sensor

Depending on your model, the sensor is held in place by one of these methods:

• Push-in clip: Press the retaining tab on the outside of the clip and push the sensor into the tub, then pull it out through the inside.
• Single screw: Remove the small Phillips screw holding the sensor bracket, then pull the sensor out.
• Twist-lock: Turn the sensor counterclockwise 90 degrees and pull straight out.

Once the mounting is released, pull the sensor probe up and out through the tub interior. The wire will come with it. From underneath (with the kick plate already removed), disconnect the wire connector from the harness if you did not already do so during testing. Remove the complete sensor assembly (probe + wire + connector).

Step 4: Install the New Sensor

Feed the new sensor probe down through the mounting hole in the tub bottom (or sump wall, depending on the location). From inside the tub, push or twist the sensor into its locked position. Verify it is secure and the probe tip extends into the water path where it can accurately read temperature during operation. From underneath, route the wire to the harness connector point and plug it in. Verify the connector clicks into place.

Step 5: Verify Installation and Test

Reinstall the lower dish rack. Reinstall the kick plate. Restore power at the breaker. Run a Normal cycle and observe:

1. The ER error code should not appear.
2. The cycle should progress through fill, wash, drain, rinse, final drain, and dry phases at normal speed.
3. After the cycle, dishes should be hot (confirming the heating element is being activated based on sensor readings).
4. The cycle length should be appropriate for the cycle selected (Normal is typically 60-90 minutes on Frigidaire models).

If the cycle runs unusually long (over 2 hours for Normal), the new sensor may be reading incorrectly. Some sensors require a calibration cycle: run the Sanitize cycle once after installation to allow the control board to calibrate to the new sensor's baseline.

Understanding the DishSense System (Gallery Models)

Frigidaire Gallery models have the DishSense system, which combines two sensors:

1. Temperature sensor (thermistor): Measures water temperature. Used to control heating element and cycle timing.
2. Turbidity sensor (soil sensor): Measures water clarity. Used to determine when dishes are clean (clear water = clean).

Both sensors are located in the sump area. If you are experiencing both short cycles AND incorrect water temperature, both sensors may need attention. However, they are separate components and fail independently. The ER error code on Gallery models can indicate either sensor. Check the specific sub-code (if displayed): ER followed by a digit may indicate which sensor is at fault. Consult your model's technical data sheet for the specific error code breakdown.

When to Call a Professional

• The ER error persists after sensor replacement. The control board input circuit for the sensor may be damaged.
• You cannot locate the sensor in your specific model (some models place it in unusual positions within the sump).
• The sensor wire was damaged during removal and needs splicing or harness replacement.
• Multiple sensors are failing simultaneously, suggesting a control board voltage regulation issue that is damaging the sensors.

Cost Comparison: DIY vs Professional

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FAQ

Q: What does the ER error code mean on a Frigidaire dishwasher? A: ER indicates a sensor error. The control board is receiving out-of-range readings from either the temperature sensor (thermistor) or the turbidity sensor (DishSense). The most common cause is a failed thermistor (open or shorted). Test the sensor resistance with a multimeter. At room temperature, expect 10,000-15,000 ohms. Open circuit or zero ohms confirms failure.

Q: How can I tell if the temperature sensor is bad vs. the heating element? A: If the heating element is bad, water stays cold but the sensor reads correctly (the cycle may run indefinitely waiting for temperature to rise). If the sensor is bad, the control board either does not activate the heater (thinks water is already hot) or activates it indefinitely (never reads target temp). Test both: element should read 10-30 ohms, sensor should read 10K-15K ohms at room temperature.

Q: Where is the temperature sensor located in a Frigidaire dishwasher? A: In the sump area at the bottom of the tub, near the heating element or filter assembly. It is a small cylindrical probe that protrudes into the water path. You can see it by removing the lower rack and looking at the bottom of the tub around the filter housing. The wire runs through the tub floor to a connector underneath.

Q: Can a bad temperature sensor cause my Frigidaire dishwasher to not dry dishes? A: Yes. If the sensor reads incorrectly high (tells the board the water is hotter than it actually is), the board may skip or shorten the heated dry phase, thinking the dishes are already hot enough for evaporative drying. Replace the sensor and the dry cycle should return to normal duration.

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