Whirlpool · Dryer
Whirlpool Dryer F42 Error Code
Heater state cannot be verified by motor control
What this error means
F42 means the motor control unit cannot detect whether the heater is on or off through its monitoring thermistor. The dryer disables heat until the sense circuit returns valid feedback.
How F42 is detected
Whirlpool dryer models lock the door or lid before energizing fill, heat, or high-speed spin. F42 means the latch switch never sent a "locked" signal to the main control, or the lock motor did not complete its travel. On Whirlpool WED9600TA, Whirlpool WED85HEFW, and similar variants, clothing caught in the gasket, a misaligned strike, or a failed latch assembly are the most common mechanical causes—not the board itself.
Inspect the door gasket perimeter and strike alignment before replacing the latch. Heater thermistor wire open at the motor control unit is reported frequently on this code. After correcting mechanical issues, disconnect power and inspect heater thermistor wiring at the mcu per the tech sheet. If the latch clicks but F42 persists, the door lock switch or wiring harness to the control board likely needs testing with a multimeter.
Do not force the door open during an active cycle; wait for the lock to release when the board de-energizes the lock motor—usually two to three minutes after canceling power on most Whirlpool units.
Common causes
- Heater thermistor wire open at the motor control unit
- Failed heater relay on the motor control board
- Shorted heating element drawing abnormal current
- Motor control unit sense circuit damaged
Step-by-step fixes
- 1Disconnect power and inspect heater thermistor wiring at the MCU per the tech sheet
- 2Check the heating element terminals for loose spade connectors
- 3Measure element resistance—it should match the spec on your model wiring diagram
- 4Replace the motor control unit if wiring and element test good but F42 persists
When to call a technician
MCU replacement on electric dryers interfaces with high-voltage heat circuits—use a qualified technician.
Affected models
- Whirlpool WED9600TA
- Whirlpool WED85HEFW
- Whirlpool WGD9600TA
Prevention & maintenance
- Wipe the door gasket weekly and avoid overloading items against the seal—F42 often starts as a slow leak or latch misalignment.
- Record when F42 appears in the cycle and whether it clears after a 60-second power reset on your Whirlpool dryer—that detail speeds diagnosis if you call service.
- Keep the model and serial number from the rating plate when ordering parts for F42; Whirlpool uses multiple revisions with different harness lengths and board firmware.
- Photograph wiring connector orientation before disconnecting any component while troubleshooting F42; reversed plugs on pumps and valves cause immediate repeat faults.