The F31 error on your Whirlpool Washer means the Moisture Control System (MCS) has detected a fault with the moisture sensor strips or their circuit. This error prevents the dryer from operating properly and requires immediate attention to restore auto-dry functionality.

Error code F31
Meaning Moisture Control System (MCS) failure – faulty moisture sensor strips or wiring
Severity Medium — Dryer won’t start or operate on auto-dry cycles, but timed dry may still work
Time to fix 15–45 minutes
Tools needed Multimeter, screwdriver set, putty knife, cleaning cloth, fine-grit sandpaper

What the F31 error means

The F31 error code indicates a problem with the Moisture Control System (MCS) in your Whirlpool dryer. The moisture sensor strips, which are metal bars located inside the drum that detect wetness in clothes, are either not functioning correctly, have failed, or there’s an electrical issue with their connection to the control board. When the control board can’t communicate properly with these sensors, it triggers the F31 error to prevent the dryer from operating incorrectly.

Common causes

  • Buildup of fabric softener residue, detergent, or mineral deposits on the moisture sensor strips
  • Corroded or oxidized moisture sensor strips that can’t conduct electrical signals properly
  • Loose, damaged, or disconnected wiring between the moisture sensors and the control board
  • Faulty moisture sensor strips that need replacement
  • Defective main control board unable to process signals from the moisture sensors
  • Poor grounding connection causing erratic sensor readings

How to fix the F31 error

  1. Clean the moisture sensor strips: Unplug the dryer and open the door. Locate the two metal sensor strips (usually on the inside front or back of the drum). Clean them thoroughly with a cloth dampened with rubbing alcohol or a mild household cleaner to remove fabric softener residue, detergent buildup, and mineral deposits. If buildup is heavy, use fine-grit sandpaper (220-grit) to gently polish the strips until shiny. Wipe clean and test the dryer.
  2. Check sensor strip connections: Remove the dryer’s top panel or front panel (depending on model) by removing screws and using a putty knife to release clips. Locate the wiring harness connected to the moisture sensor strips. Inspect for loose connections, corrosion, or damaged wires. Disconnect and reconnect the harness firmly to ensure a solid connection. Check wire terminals for corrosion and clean if necessary.
  3. Test the moisture sensor strips with a multimeter: With the dryer unplugged, disconnect the wiring harness from the moisture sensors. Set your multimeter to the lowest resistance (ohms) setting. Touch one probe to each sensor strip. You should get a reading of infinite resistance when dry. Wet your finger and touch both strips simultaneously – resistance should drop to nearly zero. If readings are inconsistent or don’t change, the sensor strips are faulty and need replacement.
  4. Inspect and test the wiring harness: Check the entire wire path from the moisture sensors to the control board for damage, pinching, or burning. Use a multimeter to test continuity through each wire. Any broken wires should be repaired or the harness replaced. Ensure all connections at the control board are secure.
  5. Replace the moisture sensor strips: If cleaning doesn’t resolve the issue and testing confirms sensor failure, order replacement moisture sensor strips specific to your Whirlpool dryer model. Remove the old strips (usually held by screws or clips), disconnect the wiring, install the new strips in the same position, and reconnect the wiring securely.
  6. Replace the control board (if necessary): If all sensors, connections, and wiring test good, the main control board may be faulty. This is the least common cause. Order a replacement control board matching your model number, disconnect power, remove the old board, transfer any necessary components, install the new board, and reconnect all wiring harnesses carefully.

FAQ

Can I still use my Whirlpool dryer with the F31 error code?
You may be able to use timed dry cycles on some models, but auto-dry cycles (which rely on moisture sensors) will not work. It’s best to fix the issue promptly to restore full functionality and prevent potential damage to clothing from over-drying on manual settings.

How often should I clean the moisture sensor strips to prevent F31 errors?
Clean the moisture sensor strips every 3-6 months as part of regular dryer maintenance. If you use fabric softener frequently or have hard water, clean them monthly. This prevents buildup that causes false readings and F31 errors.

Will the F31 error clear itself, or do I need to reset the dryer?
The F31 error will not clear on its own – you must fix the underlying problem. After repairs, unplug the dryer for 5 minutes to reset the control board, then plug it back in. If the repair was successful, the error should not return when you restart the dryer.