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Error code reference

Maytag Range Error Code 3d21

Temperature sensor shorted

Maytag codesMaytag range codes

Temperature sensor shorted — sensor resistance reads 0 ohms; disables all cook functions for cavity. Display shows BAKE flashing.

First step from the service manual

Disconnect sensor and measure resistance; replace sensor if shorted.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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What 3d21 means on a Maytag range

Error code 3d21 on a Maytag range indicates the control board has detected a short circuit condition in the upper or single oven cavity temperature sensor circuit. Specifically, the sensor resistance has dropped to approximately 0 ohms, which is outside any valid operating range. The control board continuously monitors the resistance value from the oven temperature sensor (also called an RTD or resistance temperature detector) to determine oven temperature. A reading near 0 ohms tells the board the sensor circuit has shorted rather than failed open, and it triggers this code to prevent unsafe operation.

For homeowners, the oven temperature sensor is a small probe mounted inside the oven cavity, typically at the back wall. It sends resistance readings to the control board so the oven knows when to cycle the heating elements on and off. When that sensor shorts out internally or its wiring shorts to ground, the board loses any meaningful temperature data. The oven cannot regulate heat safely under this condition.

This code most commonly points to a failed temperature sensor, but damaged wiring between the sensor and control board can produce the same result. Checking the sensor's resistance with a multimeter is the correct first step before ordering parts.

Source: manufacturer service documentation.

Common causes of 3d21

  1. 01

    Failed oven temperature sensor (internal short)

    Part replacement

    The temperature sensor itself has shorted internally, causing its resistance to read near 0 ohms. This is the most common cause of 3d21 and requires replacing the sensor probe.

  2. 02

    Shorted sensor wiring harness

    Part replacement

    The wiring harness connecting the temperature sensor to the control board has shorted, either wire-to-wire or wire-to-ground, producing a near-zero resistance reading at the board. This can result from wiring routed too close to the oven cavity walls or from physical damage over time.

  3. 03

    Damaged sensor connector or terminal pins

    Part replacement

    Corrosion, heat damage, or a crushed connector at the sensor harness plug can create a short between the two sensor terminals, mimicking a failed sensor. Inspecting and cleaning or replacing the connector may resolve the code without replacing the full sensor.

  4. 04

    Faulty control board

    Part replacement

    If the sensor and all wiring test correctly with a multimeter but the code persists, the control board's sensor input circuit may have failed internally. This is the least likely cause but should be considered after ruling out the sensor and harness.

See the test procedure for each cause

Frequently asked questions about 3d21

What does error code 3d21 mean on a Maytag range?
Code 3d21 means the control board detected a short circuit in the upper or single oven cavity temperature sensor. The sensor's resistance has dropped to approximately 0 ohms, which is not a valid reading. The board cannot determine oven temperature under this condition and disables the oven to prevent unsafe operation.
How do I fix error code 3d21 on a Maytag range?
Start by testing the oven temperature sensor resistance with a multimeter. Disconnect the sensor from the wiring harness and measure resistance across its two terminals. A working sensor reads roughly 1,000 to 1,100 ohms at room temperature, not near 0. If the reading is near 0, replace the sensor. If the sensor tests correctly, inspect the wiring harness between the sensor and control board for any shorts or damaged insulation.
Can I still use my Maytag range with a 3d21 error code active?
No. When code 3d21 is active, the oven cavity involved cannot regulate temperature because the control board has no valid sensor data. Running the oven without functional temperature control creates a risk of overheating and is not safe. Surface burners on a gas or electric range may still function, but the affected oven should not be used until the sensor or wiring fault is resolved.
How much does it cost to fix a 3d21 error on a Maytag range?
An oven temperature sensor is typically a low-cost part, often ranging from $20 to $60 depending on the specific Maytag model. Replacing it yourself is generally a simple repair requiring only a screwdriver and takes under 30 minutes in most cases. If a wiring harness replacement or control board is needed instead, parts and labor costs rise significantly. A professional service call typically adds $80 to $150 in labor on top of part costs.
How do I test the oven temperature sensor on a Maytag range showing code 3d21?
Power off the range and allow the oven to cool completely. Pull the range away from the wall and access the sensor connector, which is usually routed through the rear panel. Disconnect the sensor from the harness and set a multimeter to measure resistance (ohms). Touch the probes to the two sensor terminals. At room temperature, a good sensor reads approximately 1,000 to 1,100 ohms. A reading near 0 confirms the sensor has an internal short and needs to be replaced.

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