How to Replace the Temperature Sensor (Thermistor) on an LG Dishwasher: Fix tE and HE Errors

The temperature sensor (thermistor) on LG dishwashers monitors water temperature and reports it to the control board. When this sensor fails, the control board cannot accurately manage the heating element — resulting in either the tE (thermistor error) code or a false HE (heater error) code. The sensor itself is a small NTC (Negative Temperature Coefficient) device that costs $10-25 and takes about 15 minutes to replace once you know where it is located.

The tE error appears when the control board receives a reading outside the expected range from the thermistor — either impossibly high, impossibly low, or no signal at all. A false HE error occurs when the sensor reports that water is not heating (because it cannot read the temperature correctly), even though the heating element is working fine.

Before You Start

• Tools needed: Phillips #2 screwdriver, multimeter, flashlight
• Parts needed: LG dishwasher thermistor/temperature sensor (model-specific, ~$10-$25)
• Time required: 15-25 minutes
• Difficulty: Beginner to Intermediate
• Safety warning: Disconnect power at the circuit breaker before accessing the sensor. The sensor itself carries only low-voltage signal, but the heating element nearby operates at 120V.

Diagnosing the Temperature Sensor

Before replacing, confirm the sensor is actually failed:

1. tE error code: This directly indicates a thermistor fault. The control board detected the sensor resistance is out of the expected range.

2. HE error with working heater: If you test the heating element resistance (10-30 ohms = good) and it checks out, but HE error still appears — the thermistor is likely giving the board false "cold" readings even though the heater is working.

3. Multimeter test: Disconnect the thermistor connector and measure resistance across its terminals. At room temperature (72F/22C), a healthy LG NTC thermistor reads approximately 40,000-60,000 ohms (40K-60K). If you get OL (open circuit), near zero, or a reading wildly outside this range — the sensor has failed.

4. Temperature response test: For a more thorough check, measure resistance at room temp, then warm the sensor tip with your hand for 30 seconds and re-measure. The resistance should decrease noticeably (NTC = resistance goes down as temperature goes up). If it does not change, the sensing element is dead.

5. Run Smart Diagnosis: The LG ThinQ app can report the actual temperature reading the board is receiving, which helps confirm whether the sensor is sending garbage data.

Step-by-Step Instructions

Step 1: Locate the Temperature Sensor

On LG dishwashers, the thermistor is located inside the tub, typically at the bottom near the sump area. Open the door and remove the lower dish rack. Remove the pull-up filter assembly (lift straight up). Look in the sump area (the recessed well at the tub floor center). The sensor is a small plastic-bodied probe with a 2-wire connector, mounted into the sump housing or the tub wall near the bottom. On some models, it protrudes from the sump sidewall; on others, it is clipped to the bottom of the tub.

Step 2: Disconnect Power and Access the Sensor

Disconnect power at the circuit breaker. If the sensor connector is accessible from inside the tub (some models have the connector just above the sump, reachable after removing the filter), you can disconnect it directly. On other models, you may need to access the underside: remove the lower access panel (4 Phillips screws along the bottom front) to reach the connector from below.

Step 3: Disconnect the Sensor Wiring

The thermistor has a 2-pin connector. Press the locking tab and pull the connector apart. On models where the connector is under the tub, trace the wires from the sensor down through the tub and locate the connector in the wiring harness beneath.

Step 4: Remove the Old Sensor

The sensor is held in place by either a small Phillips screw, a plastic retaining clip, or a friction-fit rubber grommet. For screw-mounted: remove the single screw and pull the sensor probe out of its housing. For clip-mounted: press the clip tab and slide the sensor free. For grommet-mounted: pull the sensor straight out of the rubber grommet (the grommet stays in place).

Step 5: Install the New Temperature Sensor

Insert the new sensor probe into the same housing/grommet. The sensing tip must make contact with water during operation — ensure it protrudes into the sump area where water collects. Secure with the screw or clip. The probe should be snug but not forced — overtightening a screw can crack the plastic sensor body.

Step 6: Reconnect Wiring

Push the 2-pin connector together until it clicks. Ensure the locking tab engages. If you accessed the connector from below, route the wire neatly along its original path, secured away from moving parts (spray arm, pump).

Step 7: Verify Sensor Installation with Multimeter

Before reassembling, verify the new sensor works. With the connector plugged in, measure resistance at the board end of the harness (or directly at the sensor connector if accessible). You should read 40K-60K ohms at room temperature. This confirms the sensor is properly connected and functioning.

Step 8: Reassemble and Test

Reinstall the filter assembly (push down into place). Replace the lower access panel if removed. Reinstall the lower dish rack. Restore power at the breaker. Start a Normal cycle. The tE/HE error should not appear. Run the cycle for at least 20 minutes to confirm the heating phase operates normally (open door after 20 min — water should be hot). Run Smart Diagnosis to verify the board reports a valid temperature reading.

Troubleshooting After Replacement

• tE error returns with new sensor: Check the wiring harness between the sensor and the control board. A damaged wire (pinched, corroded, or mouse-chewed) can cause open/short readings that mimic sensor failure. Trace the wire and look for damage.
• HE error persists: If the new sensor reports correct temperature but HE still appears, the heating element itself may have actually failed in the time between diagnosis and replacement. Test the heater resistance (10-30 ohms).
• Erratic temperature readings on Smart Diagnosis: The connector may not be fully seated, or there is corrosion on the connector pins. Disconnect, clean the pins with contact cleaner, and reconnect firmly.
• Sensor reads correct at room temp but fails during cycle: The sensor probe may not be in proper contact with water. Verify it protrudes into the sump where water level reaches during operation.

When to Call a Professional

• The wiring harness between sensor and board is damaged in an area you cannot access
• Both the sensor and heating element test good but HE/tE errors persist — control board issue
• The sensor mounting area in the sump is corroded or damaged
• You cannot locate the sensor position on your specific model

Cost Comparison: DIY vs Professional

Need Professional Help?

• Dishwasher repair service
• LG appliance repair
• Dishwasher repair cost guide

FAQ

Q: What type of temperature sensor does LG use in dishwashers? A: LG uses NTC (Negative Temperature Coefficient) thermistors. These sensors decrease in resistance as temperature increases. At room temperature they read approximately 40K-60K ohms. At wash temperature (130-150F) they read approximately 5K-15K ohms.

Q: Can a failed temperature sensor cause the dishwasher to overheat? A: Theoretically yes — if the sensor reports falsely low temperature, the control board would keep the heater on. However, LG dishwashers have a thermal fuse as a backup safety that cuts power if temperature exceeds safe limits, preventing damage.

Q: How do I tell the difference between tE and HE errors? A: tE specifically means the sensor signal is out of range (open/short/impossible reading). HE means the expected temperature rise was not detected. tE almost always indicates sensor failure. HE can be either the sensor OR the heater. Test both before ordering parts.

Q: Where exactly is the temperature sensor located inside the LG dishwasher tub? A: It is at the bottom of the tub, in or near the sump area (the recessed well at the center floor). Remove the lower rack and the pull-up filter to see it. It looks like a small plastic probe with two wires, mounted to the sump wall or floor.

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