Whirlpool · Dryer

F4

Thermistor Open or Shorted

Severity

Medium

When a Whirlpool Dryer shows F4 on its display, the internal diagnostic system has flagged a condition known as "Thermistor Open or Shorted". Most repairs for this code are straightforward and can be completed at home.

Owner's Summary

Your dryer's temperature sensor has an electrical fault — either a complete break or a short circuit inside the sensor. This is an inexpensive part and a straightforward replacement.

Symptoms

Whirlpool dryer running cold cycles or overheating, F4 error code

Common Causes

Open circuit thermistor
Shorted thermistor
Corroded thermistor connector
Wiring harness fault

How to Fix

1 Test thermistor resistance at room temperature — open circuit reads infinite, shorted reads near zero
2 Inspect and clean thermistor connector with contact cleaner
3 Test wiring harness continuity
4 Replace thermistor if out of spec

Tools You'll Need

Multimeter Electrical Contact Cleaner Flashlight

These are simple, low-risk fixes most homeowners can do with tools already in a basic toolbox.

Technical Explanation

F4 is generated when the CCU reads a thermistor resistance value outside both the open-circuit and closed-circuit valid ranges. The board disables the heater relay to avoid operating with unreliable temperature feedback.

Is It Safe to Keep Using?

No immediate safety risk, but avoid running unattended cycles until resolved given the lack of reliable temperature feedback.

Technician's Pro Tip

Always test thermistor resistance with the dryer fully unplugged. A reading exactly at 0 ohms or showing 'OL' (open loop) on your multimeter confirms a failed sensor rather than a wiring issue.

Related Codes

F21 — Whirlpool Washing Machine

Long Drain Time or Drain Pump Fault

High

F20 — Whirlpool Washing Machine

No Water Detected

High

F7E1 — Whirlpool Washing Machine

Motor Speed Sensing Error

High

Frequently Asked Questions

What does error code F4 mean on a Whirlpool Dryer?

Code F4 on a Whirlpool Dryer indicates "Thermistor Open or Shorted." In practice, the most common trigger is open circuit thermistor. Severity is rated medium, and typical repair costs range from $15 to $100.

Can I fix F4 myself, or do I need a technician?

Many cases of F4 can be resolved without a technician. The first step to try: test thermistor resistance at room temperature — open circuit reads infinite, shorted reads near zero. If that doesn't clear the code, work through the remaining steps in the "How to Fix" section above before assuming a part needs replacing.

Is it safe to keep using my dryer with code F4 showing?

No immediate safety risk, but avoid running unattended cycles until resolved given the lack of reliable temperature feedback.

How much does it cost to repair F4 on a Whirlpool Dryer?

Repair costs for code F4 typically range from $15 to $100. Thermistor: $15–$30; Labor: $40–$100. Costs on the low end usually reflect a DIY fix with no parts required, while the high end reflects a part replacement plus professional labor.

Estimated Repair Cost USD

$15 – $100

Thermistor: $15–$30; Labor: $40–$100