Kenmore Microwave E1 Error Code — What It Means
The E1 error code on a Kenmore microwave indicates a thermistor sensing fault. The control board is not receiving the expected temperature feedback signal from the thermistor circuit, so it flags an error and halts operation. This is a sensor problem, not a humidity sensor issue (which would show as E11) or a door switch fault.
The thermistor is a temperature sensor that monitors internal conditions during cooking. When it fails, drifts out of range, or loses electrical connection, the control board cannot verify safe operating temperatures and throws the E1 code. Common culprits are a failed thermistor itself, damaged or corroded wiring, or occasionally a control board input failure.
Common Causes
- Failed thermistor The temperature sensor has gone open circuit, shorted, or drifted out of its normal resistance range.
- Loose or corroded wiring The thermistor harness connector has corroded terminals, loose pins, or broken wire strands interrupting the signal.
- Heat-damaged connector The thermistor connector has melted, burned, or developed high-resistance contact from prolonged heat exposure.
- Control board input failure The main control board’s thermistor sensing circuit has failed internally even though the sensor and wiring test good.
Step-by-Step Fix
- Disconnect power by unplugging the microwave or switching off the breaker, then wait two minutes and restore power to see if the code clears (transient control glitch).
- Identify the OEM builder by noting the first three digits of your Kenmore model number, since Kenmore is a brand label and the actual manufacturer determines parts and procedures.
- Remove the outer cabinet panels to access the interior cavity and locate the thermistor, typically a small round sensor with two wires clipped or plugged into the magnetron or cavity wall.
- Inspect the thermistor and harness for burn marks, melted insulation, corroded pins, or loose connectors, and wiggle the connector to check for intermittent contact.
- Test the thermistor resistance using a multimeter set to ohms, disconnecting it from the harness and comparing the reading to your model’s specification table (if the reading is infinite, zero, or wildly off, replace the sensor).
- Check wiring continuity from the thermistor connector back to the control board plug to rule out a broken wire or bad crimp in the harness.
- Replace the thermistor or control board based on test results: if the sensor is out of range, install a new thermistor for your exact OEM platform; if the sensor and wiring are good, replace the control board.
Parts Often Needed
| Part | Notes |
|---|---|
| Microwave thermistor / temperature sensor | Amazon | Match by Kenmore model number and OEM manufacturer (first three digits of model). |
| Thermistor wire harness | Amazon | Order if connector is burned or harness wires are broken; often sold with the sensor. |
| Microwave main control board | Amazon | Required only if thermistor and wiring test good but E1 persists; confirm model and voltage. |
When to Call a Pro
Call a professional if you are uncomfortable working inside a microwave cabinet (high-voltage capacitor hazard even when unplugged), if you do not have a multimeter and cannot test the thermistor safely, or if you replace the sensor and harness but the E1 code returns immediately. A qualified appliance technician can discharge the high-voltage capacitor, test the control board input circuit, and source the correct OEM thermistor for your specific Kenmore platform without trial-and-error parts swapping.