LG Oven Error Code C-20

The C-20 error code on an LG oven indicates a fault detected in the oven temperature sensor circuit. Specifically, the control system has identified that the sensor is either open (a complete break in the circuit, producing infinite or out-of-range resistance) or shorted (a direct connection causing abnormally low resistance). This fault is detected while the oven is actively operating, meaning the control board is attempting to regulate temperature and is receiving a signal from the sensor that falls outside acceptable parameters. The oven temperature sensor, typically a resistance temperature detector (RTD), changes its resistance value in a predictable way as temperature changes, and any deviation beyond the expected range triggers this code.

The oven sensor circuit runs from the sensor probe inside the oven cavity through a wiring harness to the main PCB (printed circuit board). A failure at any point along this circuit can produce the C-20 code. The most important first diagnostic step is to check whether the sensor connector is properly seated at the main PCB, as a loose or partially disconnected connector can mimic both an open and a shorted circuit condition. Beyond the connector, the wiring harness itself should be inspected for damage such as pinched wires, heat-related insulation breakdown, or corrosion at the connector pins.

If the connector and wiring are intact, the sensor probe itself may have failed internally. A failed RTD sensor will typically read either very high resistance (open) or near-zero resistance (short) when measured with a multimeter at room temperature. Replacing a faulty sensor is a straightforward repair in most cases, but the main PCB should also be considered if the wiring and sensor both test within spec.