Microwave displays E2 and will not start heating; timer may count down but no cooking occurs.

Safety first: Unplug the microwave. Do not operate a microwave with covers removed. High voltage is present even when unplugged due to the capacitor; avoid the high-voltage section.

• Allow unit to cool: If the microwave was used for an extended period, let it cool for 30–60 minutes, then plug back in and test. Some Oster models will show E2 after an overheat condition.
• Check vents: Ensure the rear and side vents are not blocked by cabinets, walls, or items. Poor ventilation can cause overheating and sensor errors.
• Inspect temperature sensor wiring: Remove the outer cabinet (screws at back and sides). Locate the cavity temperature sensor (often a small probe or thermistor clipped to the side or top of the cooking cavity). Check that its connector is firmly seated on the wiring harness and that wires are not pinched or burned.
• Test the sensor (advanced): With a multimeter set to resistance (ohms), measure the sensor across its two terminals. Compare to Oster service specs for your model (typically a few kΩ at room temperature). If it reads open (infinite) or short (near 0 Ω), replace the sensor.
• If wiring and sensor are good: The main control board’s sensor circuit may be defective and will need replacement by a professional.