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Error code · Microwave

Code 3d21 on Whirlpool Built-In Microwaves: Oven Sensor or Wiring

The 3d21 message on Whirlpool built-in microwaves and microwave drawers, model WMC50522AS included, relates to temperature sensing inside the oven. The oven temperature sensor, the control that reads it, or the wiring in between could be…

Medium · inspection needed
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Code
3d21
Appliance
Microwave
Brand
Whirlpool
Warranty
30-day workmanship

What 3d21 means

The 3d21 message on Whirlpool built-in microwaves and microwave drawers, model WMC50522AS included, relates to temperature sensing inside the oven. The oven temperature sensor, the control that reads it, or the wiring in between could be behind it. Because it describes a circuit, the display is the only thing you see, plus an oven that may stop heating while the reading is in question.

Common causes of 3d21

  • Oven temperature sensor giving an unexpected reading
  • Control interpreting the sensor signal
  • Wiring problem along the sensor circuit
  • Short-lived reading problem that disappears after a restart
✓ One safe check you can try

1. Turn off the circuit breaker feeding the microwave for one minute. 2. Turn the breaker on again. 3. Watch the oven for a minute to check that 3d21 stays away. 4. Verify operation with a short test run. 5. If the code returns, stop and call us.

! Why to stop there
  • If the code returns, we measure the sensor circuit and check the control and wiring around it
  • We confirm the cause by testing before we propose a part
  • You approve a written price first; workmanship is warranted for 30 days
Opening a panel yourself does not automatically cancel a manufacturer warranty, but it can cause accidental damage, and some manufacturers set their own service conditions. Check your warranty terms, or ask us, before deciding.
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Other Microwave codes

Feature Not Available or Fault DetectedWhirlpool Built-in Microwave Message "Feature Not Available": Retry or Cut Power LOCWhirlpool Microwave LOC on the Display: Control Lock Is On PFWhirlpool Over-the-range Microwave Showing PF: Power Failure Indicator Press Cancel to ResetWhirlpool Built-in Microwave Message "Press Cancel to Reset": Error Cleared by Cancel F8 E4Whirlpool Microwave Drawer Error Code F8 E4: Exhaust Air Temperature Sensor Probe or Insert ProbeWhirlpool Built-in Microwave Asking for "Insert Probe": Seat the Meat Probe F8E5Whirlpool Microwave Code F8E5: Exhaust Air Temperature Sensor PUSH or PSHWhirlpool Built-in Microwave Shows PUSH or PSH: Press Start
3d213d21 questions
How do I know whether 3d21 is the sensor or the control?

You cannot tell from the display, since the code covers the sensor, the control and the wiring. We measure the circuit to find out which one is responsible.

The code vanished after a reset. Should I worry?

If it stays gone, carry on. If 3d21 appears again on another day, the circuit has a real issue and should be tested instead of reset again and again.

Will you tell me if an old microwave is not worth fixing?

Yes. We say plainly when a repair costs more than the unit is worth, and we repair the many older built-ins still working in Houston homes.

Book a visit

Still seeing 3d21?

A technician diagnoses it on site and gives you the price in writing before any work starts.

(713) 589-6107