F4
Whirlpool Dryer
Severity: ModerateWhat Does This Error Mean?
The F4 error means the inlet thermistor in your Whirlpool dryer is reading an abnormal value. The inlet thermistor monitors the temperature of air entering the drum. The dryer stops to protect itself from overheating or running at the wrong temperature.
Affected Models
- WED5000DW
- WED8000DW
- WED9290FW
- WED4950HW
- Most Whirlpool electric and gas dryers
Common Causes
- The inlet thermistor sensor has failed and is giving an incorrect reading
- Wiring to the inlet thermistor is loose, broken, or has a bad connection
- The heating element is not working properly, causing abnormal inlet temperatures
- A blocked or restricted lint screen is affecting airflow and temperature readings
- The control board is misinterpreting the thermistor signal
How to Fix It
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Unplug the dryer from the outlet and clean the lint screen.
Poor airflow can skew temperature readings and trigger thermistor errors.
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Plug the dryer back in and run a power reset cycle.
Wait 5 minutes before plugging back in to allow the control board to fully reset.
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Locate the inlet thermistor — it is usually on the back wall of the drum or near the heating element housing.
Refer to your model's service manual if unsure of the exact location.
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Test the thermistor with a multimeter for proper resistance.
At room temperature, most Whirlpool thermistors should read around 10,000–50,000 ohms. Check your service manual for the exact spec.
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Replace the inlet thermistor if it reads open, shorted, or out of specification.
This is a straightforward replacement — the sensor simply unplugs and the new one clips into place.
When to Call a Professional
If replacing the inlet thermistor does not clear the F4 error, the heating element or control board may be at fault. A technician can run a full diagnostic to isolate the problem. Inlet thermistor parts typically cost $20–$60.
Frequently Asked Questions
What is the difference between the F3 and F4 errors on a Whirlpool dryer?
F3 relates to the exhaust thermistor, which measures outgoing air temperature. F4 relates to the inlet thermistor, which measures incoming air temperature. Both sensors protect the dryer from running at unsafe temperatures.
Can I test the thermistor myself without a multimeter?
Not reliably. A multimeter is the only accurate way to test a thermistor. Multimeters are inexpensive — around $15–$25 at a hardware store. They are useful for many home appliance repairs, so it's a good investment.
Is the F4 error dangerous to ignore?
You should not ignore it. The thermistor protects the dryer from overheating. A failed thermistor can allow temperatures to get too high, which is a fire risk. Fix it promptly — the repair is usually inexpensive.