GE Profile Washer Error Code 66: Water Temperature... | appliancefaults.com

Technical Background:

The Main Control Unit (MCU) monitors the water temperature via the water temperature sensor. The sensor is a thermistor whose resistance changes with temperature. The MCU applies a voltage to the sensor circuit and reads the voltage drop. An open circuit prevents voltage flow to the MCU, triggering the error code. Expect to see 5V DC supplied to the sensor circuit from the MCU. The MCU interprets the return voltage to determine the water temperature.

Symptoms:

The washer displays error code 66. The water temperature may be incorrect, or the washer may not heat the water at all. The washer cycle may be interrupted.

Possible Causes:

Open or shorted water temperature sensor.
Wiring harness damage to the water temperature sensor.
Loose or corroded connections at the sensor or control board.
Faulty main control board (MCU).
Water temperature sensor not fully submerged in water during testing.

Solution:

1

Disconnect power to the washer at the breaker panel.
2

Locate the water temperature sensor; typically near the heater element, accessed from the rear panel. Remove the rear panel using a 1/4-inch nut driver.
3

Disconnect the wiring harness from the water temperature sensor.
4

Using a multimeter set to the ohms setting, measure the resistance across the sensor terminals. Expect a reading of approximately 10-20k ohms at room temperature (70-75°F). An open circuit (infinite resistance) confirms a faulty sensor. Check the sensor's datasheet for specific resistance values at given temperatures.
5

Inspect the wiring harness and connections for damage or corrosion. Use a wire brush to clean corroded connections or replace the harness if damaged.
6

If the wiring and sensor test okay, the main control board (MCU) might be faulty. Replace the MCU. Ensure the new MCU is correctly programmed for your washer model.
7

Reconnect all wiring, restore power at the breaker panel, and test the washer's operation. Run a test cycle to confirm the error code is cleared and the water heats correctly.

Safety Warning:

Disconnect power to the washer at the breaker panel before performing any repairs. Use Lock-Out/Tag-Out (LOTO) procedures to prevent accidental re-energizing of the circuit. High voltage is present when the washer is powered on.

Prevention:

Periodically inspect the wiring and connections to the water temperature sensor for signs of corrosion or damage. Ensure the water temperature sensor is free from debris. Use a water softener if you have hard water to minimize mineral buildup on the sensor.

Expert Tip:

Many GE washers have a service mode. To enter service mode, simultaneously press and hold the Start/Pause and Soil Level buttons for 3 seconds. Error codes can be retrieved and cleared in service mode. Refer to the service manual for your specific model for complete instructions. This might override the error and allow you to continue troubleshooting.

Frequently Asked Questions

•What is the resistance value I should expect from the water temperature sensor at different temperatures?

Refer to the GE service manual or the sensor's datasheet for the specific resistance values at various temperatures. The resistance generally decreases as the temperature increases.

•Where exactly is the water temperature sensor located in my GE Profile washer?

The water temperature sensor is typically located near the heater element at the bottom of the outer tub, accessible from the rear of the machine once the back panel is removed. It's often clipped or screwed into the heater assembly.

•How do I program the new main control board (MCU) after replacing it?

The new MCU may need to be programmed with your washer's specific model information. Some MCUs come pre-programmed, while others require a USB programmer and software available through authorized GE appliance parts distributors. Consult the replacement MCU's instructions or a qualified appliance technician for assistance.

GE Profile Washer Error Code 66: Water Temperature Sensor Open Circuit Troubleshooting

Technical Background:

Symptoms:

Possible Causes:

Solution:

Safety Warning:

Prevention:

Expert Tip:

Frequently Asked Questions

•What is the resistance value I should expect from the water temperature sensor at different temperatures?

•Where exactly is the water temperature sensor located in my GE Profile washer?

•How do I program the new main control board (MCU) after replacing it?

Related questions

Technical Background:

Symptoms:

Possible Causes:

Solution:

Safety Warning:

Prevention:

Expert Tip: