Hotpoint Dryer Error Code E70: NTC Sensor Fault... | appliancefaults.com

Technical Background:

The main control board (MCU) monitors the temperature inside the dryer drum using the NTC sensor. The NTC sensor's resistance changes with temperature. The MCU reads the voltage drop across the sensor. If the MCU detects a resistance value outside the acceptable range or an open/short circuit, it triggers the E70 error and stops the drying cycle. The voltage path involves a 5V DC reference voltage from the MCU, a resistor network, and the NTC sensor itself, creating a voltage divider.

Symptoms:

The homeowner observes that the dryer displays an E70 error code. The dryer may not heat properly, or it may shut down prematurely during the drying cycle.

Possible Causes:

Faulty NTC (Negative Temperature Coefficient) sensor.
Loose or corroded wiring harness connections to the NTC sensor.
Damaged wiring between the NTC sensor and the main control board (MCU).
Defective main control board (MCU).
Blocked dryer vent causing overheating.

Solution:

1

Disconnect power to the dryer at the breaker panel.
2

Locate the NTC sensor, typically on the blower housing or heating element housing.
3

Inspect the wiring and connections to the NTC sensor for damage or corrosion. Clean or repair as needed.
4

Using a multimeter, measure the resistance of the NTC sensor at room temperature (approximately 70°F). A typical NTC sensor reads between 10,000 and 50,000 ohms. Consult the dryer's service manual for the specific resistance value.
5

If the resistance is outside the specified range, replace the NTC sensor. Replacements are inexpensive.
6

If the NTC sensor tests within range, check the wiring harness continuity between the sensor and the main control board using your multimeter. Repair any open circuits or shorts.
7

If the wiring is good, suspect a faulty main control board (MCU) and consider replacing it. This requires careful diagnosis, and sometimes licensed technician assistance is the best course.

Safety Warning:

Always disconnect power to the dryer at the breaker panel before performing any repairs. Use Lock-Out/Tag-Out (LOTO) procedures to ensure the dryer remains de-energized during service. Dryer circuits carry 240V AC – a potentially lethal voltage.

Prevention:

Regularly clean the dryer vent ductwork to prevent lint buildup and overheating. Annually inspect the wiring connections to the NTC sensor and other dryer components for corrosion or damage. A clean vent ensures proper airflow and prolongs the life of the dryer and its components.

Expert Tip:

Some Hotpoint dryers have a diagnostic mode. Simultaneously press and hold the Start/Pause and Signal buttons for 3 seconds to enter the diagnostic mode. This may display error codes and allow you to test individual components. Cycle power to exit.

Frequently Asked Questions

•What is the typical resistance range for the NTC sensor at room temperature for this specific Hotpoint dryer?

Refer to the dryer's service manual for the exact resistance value at a given temperature. A general range is 10,000-50,000 ohms at 70°F, but the specific value can vary.

•How do I test the wiring harness continuity between the NTC sensor and the main control board?

Disconnect power to the dryer. Disconnect both ends of the wiring harness. Set your multimeter to the continuity setting. Place one probe on a pin at one end of the harness and the other probe on the corresponding pin at the other end. You should hear a beep or see a reading close to 0 ohms, indicating continuity. Repeat for each wire in the harness.

•If I replace the main control board, will it require any programming or calibration?

Some main control boards may require programming or calibration after installation. Consult the service manual or the control board vendor for specific instructions. Some boards are plug-and-play, while others require model-specific configuration.

Hotpoint Dryer Error Code E70: NTC Sensor Fault Troubleshooting

Technical Background:

Symptoms:

Possible Causes:

Solution:

Safety Warning:

Prevention:

Expert Tip:

Frequently Asked Questions

•What is the typical resistance range for the NTC sensor at room temperature for this specific Hotpoint dryer?

•How do I test the wiring harness continuity between the NTC sensor and the main control board?

•If I replace the main control board, will it require any programming or calibration?

Related questions

Technical Background:

Symptoms:

Possible Causes:

Solution:

Safety Warning:

Prevention:

Expert Tip: