Whirlpool Microwave Error Code ERR B

ERR B on a Whirlpool microwave indicates that the control board is receiving no pulse signals from the weight sensor, or that the sensor's operating frequency has dropped below the minimum threshold of 4267 Hz. Weight sensors in these microwaves function as frequency-based transducers: they generate oscillating electrical pulses that the control board reads to calculate the load placed on the turntable or sensor platform. When those pulses stop entirely or fall below the 4267 Hz floor, the board interprets this as a sensor failure and triggers ERR B to prevent inaccurate auto-cook or sensor-cook operations.

The most common root causes fall into two categories: a failed weight sensor and a wiring or connection fault between the sensor and the control board. The sensor itself can fail due to mechanical damage, moisture intrusion, or component fatigue over time, causing it to stop generating pulses or output a degraded signal. Loose connector pins, corroded terminals, or a damaged wire harness running from the sensor to the board can also interrupt the pulse signal entirely, producing the same ERR B result even when the sensor itself is functional.

Because this code specifically involves a frequency threshold, intermittent ERR B appearances may point to a marginal sensor that still generates pulses but not consistently above 4267 Hz. A sensor outputting a weak or drifting signal will cause the error to appear under some conditions but not others. Diagnosing this accurately requires checking connector integrity at both ends of the sensor harness, inspecting the sensor for visible damage or corrosion, and if equipment is available, verifying pulse output frequency directly at the sensor terminals.