LG Microwave Error Code E-28

The E-28 error code on an LG microwave indicates a sensor short error, meaning the humidity or moisture sensor used in sensor cooking modes has detected an abnormal short condition across its terminals. This sensor monitors steam output from food during cooking and signals the control board to adjust cook time and power levels accordingly. When the sensor's two terminals show a slight short, the control board interprets this as a fault and halts normal operation to prevent inaccurate cooking results or potential component damage.

The diagnostic process begins by checking whether both terminals of the sensor are slightly shorted to each other. A slight short, rather than a dead short, suggests the sensor element itself may have degraded, moisture may have contaminated the sensor housing, or a wiring connection is creating an unintended low-resistance path between the terminals. Under normal operating conditions, the sensor should present a predictable resistance profile that changes in response to steam levels. Any deviation toward a shorted state will trigger this error.

Because this error is specifically tied to the sensor circuit, component failures elsewhere in the microwave are unlikely to be the root cause. The sensor assembly, its wiring harness, and the connector interface at the control board are the primary areas to inspect. Technicians should visually inspect for moisture intrusion, burnt contacts, or damaged insulation before measuring terminal resistance to confirm the fault.