Whirlpool Microwave Error Code F3-E3

The F3-E3 error code on a Whirlpool microwave indicates that the oven cavity temperature has exceeded 510°C (950°F) during CLEAN mode operation. This code is generated by the control board when the temperature sensor (also called the cavity sensor or oven sensor) reports a value above the allowable threshold. The sensor is a resistive temperature device, meaning its resistance changes predictably with temperature. At 21°C (70°F), the sensor should read approximately 1080 ohms, increasing by roughly 2 ohms per degree Celsius as temperature rises. When readings spike beyond the expected range for CLEAN mode, the control board interprets this as a dangerously high temperature condition and locks out operation.

The most common triggers for this fault fall into two categories: a faulty temperature sensor producing inaccurate high readings, or a hardware problem on the control board itself. A failed sensor can report runaway temperatures even when the cavity is within a safe range, causing a false F3-E3 fault. On the control board side, relays that switch the heating circuit can fail in a welded-closed position, meaning they remain energized regardless of the control signal. A welded relay would allow continuous heating with no ability for the board to cut power, resulting in genuine overtemperature conditions rather than a false reading.

Diagnosing this code requires checking the sensor wiring harness and connector first, then measuring sensor resistance with a multimeter to confirm it matches the expected value for the ambient temperature. If resistance checks out and connections are secure, the control board relays become the primary suspect. Relay failures of this type typically require full control board replacement rather than component-level repair.