Microwave displays F4 and will not run or stops during operation, often associated with temperature or sensor cooking modes.

Safety: Unplug the unit or turn off the breaker. Allow the microwave to cool before working near the cavity or convection components.

• Inspect sensor wiring: Locate the oven temperature sensor and follow its wiring harness. Look for spots where the insulation may be rubbed through and touching metal, causing a short.
• Check sensor resistance: Disconnect the sensor and measure resistance with a multimeter. A very low resistance (near 0 Ω) or readings far from the Monogram spec indicate a shorted sensor.
• Dry connectors: If the error appeared after heavy steam use, disconnect the sensor connector, dry it thoroughly, and allow the cavity to air out. Reconnect and test.
• Replace sensor or harness: If the sensor is shorted or the harness is damaged, replace the temperature sensor / thermistor and/or sensor wiring harness with OEM Monogram parts.
• Control board: If sensor and wiring test correctly, the electronic control board sensor circuit may be shorted and require replacement.