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Error code reference

Kenmore Range Error Code 1d21

Upper oven temperature sensor resistance too high (>2787 ohms at door lock)

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Upper oven temperature sensor resistance too high (>2787 ohms at door lock) – disables all cooking functions for the cavity.

First step from the service manual

Check temperature sensor resistance and wiring.

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

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What 1d21 means on a Kenmore range

The 1d21 error code on a Kenmore range indicates that the upper oven temperature sensor is returning a resistance value exceeding 2787 ohms at the point of door lock engagement. The temperature sensor, also called an RTD (resistance temperature detector) or oven thermistor, is designed to change resistance in a predictable way as oven temperature changes. When resistance climbs above the upper threshold, the control board interprets this as an out-of-range or open-circuit condition and disables all cooking functions for the upper oven cavity as a safety measure.

The most direct cause of this fault is a failed temperature sensor with an open or intermittently open internal element, which causes resistance to spike beyond the acceptable range. However, wiring issues between the sensor and the control board are equally worth investigating. Damaged insulation, a corroded connector, or a broken wire in the sensor harness can introduce unwanted resistance into the circuit, mimicking a failed sensor. Always measure resistance directly at the sensor connector before assuming the sensor itself has failed.

Because the fault triggers at door lock engagement, it is specifically tied to the control board polling sensor data during a critical safety checkpoint. Until the resistance reading returns to within the acceptable operating range, the board will not allow the upper oven to operate. Clearing the error without correcting the underlying resistance issue will result in the code returning immediately or shortly after a cook cycle is initiated.

Source: manufacturer service documentation.

Common causes of 1d21

  1. 01

    Failed upper oven temperature sensor

    Part replacement

    The sensor element itself has opened internally, causing resistance to exceed 2787 ohms. Measuring resistance directly at the sensor leads with a multimeter will confirm if the sensor is out of specification.

  2. 02

    Damaged or broken sensor wiring harness

    Part replacement

    A broken, pinched, or burned wire in the harness connecting the sensor to the control board adds resistance to the circuit. Visually inspect the wiring along its entire run and check for continuity.

  3. 03

    Corroded or loose sensor connector

    Wiring / connection

    Corrosion or a loose fit at the connector terminals can interrupt the circuit and push resistance readings above the threshold. Disconnect and inspect the connector for discoloration, moisture damage, or backed-out terminals.

  4. 04

    Faulty oven control board

    Part replacement

    If the sensor and all wiring measure correctly but the error persists, the control board may be misreading the sensor input due to a failed input circuit. This is the least common cause and should only be diagnosed after the sensor and wiring have been ruled out.

See the test procedure for each cause

Frequently asked questions about 1d21

What does 1d21 mean on a Kenmore range?
The 1d21 code means the upper oven temperature sensor is reading a resistance above 2787 ohms at the door lock checkpoint. This tells the control board that the sensor signal is outside the acceptable range. As a result, the board disables all cooking functions for the upper oven cavity until the condition is resolved.
Can I fix the 1d21 error myself?
A knowledgeable DIYer can diagnose this fault by using a multimeter to measure the resistance of the temperature sensor directly at its connector. If the sensor reads above 2787 ohms or shows an open circuit, replacing it is a straightforward repair involving removing a few mounting screws and unplugging the harness. Wiring inspection requires careful attention along the full harness run inside the oven cavity.
Is it safe to use my Kenmore range while the 1d21 code is active?
The upper oven cooking functions are disabled by the control board when this code is active, so the upper cavity cannot be used for baking or broiling. Surface burners on a gas or electric range may still function depending on the model. It is best not to attempt to bypass the error and instead address the sensor issue before resuming normal use.
How much does it cost to repair the 1d21 error on a Kenmore range?
If the repair requires only a new upper oven temperature sensor, parts typically cost between $20 and $60 depending on the specific model. If professional installation is needed, total repair costs including labor generally fall in the range of $100 to $200. A control board replacement, if ultimately required, can push costs higher, typically $150 to $350 for parts alone.
Will resetting the Kenmore range clear the 1d21 error code?
Resetting the range by cutting power at the breaker or unplugging it may temporarily clear the code from the display. However, if the underlying sensor resistance is still above 2787 ohms, the error will return as soon as the control board runs its next sensor check, usually at the start of the next cook cycle or door lock event. A reset is not a fix and the root cause must be corrected.

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