Maytag Oven Error Code 3d21

Code 3d21 means the control board has detected that the upper or single oven temperature sensor is shorted, with resistance reading 0 ohms. A healthy sensor reads around 1080 ohms at room temperature (70°F). A reading of 0 ohms tells the board the sensor circuit has failed and the oven cannot regulate temperature accurately.

No. With a shorted temperature sensor, the control board cannot accurately monitor oven temperature. Depending on how the board responds to the fault, the oven may not heat at all, or in a worst case, heating elements could operate without proper temperature feedback. Do not use the oven for cooking until the sensor or wiring is repaired.

Yes. If the wires running from the temperature sensor to the control board are pinched, burned, or have bare conductors touching each other, the board will see 0 ohms on the sensor circuit and trigger 3d21 even if the sensor itself is fine. Always test resistance at the sensor connector first, then at the control board end of the harness to isolate where the short is located.

Start by unplugging the oven and locating the temperature sensor inside the oven cavity, typically mounted at the rear wall. Disconnect the sensor connector and measure resistance across the sensor terminals with a multimeter. If you read 0 ohms, the sensor is shorted and needs to be replaced. If the sensor reads correctly near 1080 ohms, inspect the wiring harness from the sensor to the control board for damage or shorts before assuming the board is at fault.

A replacement oven temperature sensor typically costs between $20 and $60 for the part, and replacing it is a repair most DIYers can complete in under 30 minutes using a screwdriver. If the wiring harness is damaged, a harness repair or replacement adds some cost and complexity. Professional appliance technician labor generally runs $100 to $200 depending on your area, making the total repair cost modest compared to replacing the oven.