LG Microwave Error Code C-20

C-20 is a temperature sensor fault code indicating that the sensor reading has fallen outside the acceptable range, specifically below 5 or above 250. This signals an open or short circuit condition in the temperature sensor circuit. When this code appears, the microwave cancels its current operation and will not run until the fault is resolved.

No, you should not attempt to operate the microwave while C-20 is active. The code causes the oven to enter cancel mode specifically to prevent operation without a functioning temperature sensor. Running the microwave without a working temperature sensor could result in overheating or uncontrolled cooking conditions.

Repair costs vary depending on the cause. If only a connector needs reseating, there may be no parts cost and a modest diagnostic labor fee, typically in the range of $50 to $100. Replacing the temperature sensor itself generally costs between $75 and $175 including parts and labor. PCB replacement, if required, is the most expensive scenario and could range from $150 to $300 or more, at which point evaluating the cost of a new unit may be worthwhile.

Some causes of C-20, such as a loose connector between the sensor housing and the PCB, can be addressed by a confident DIYer who is comfortable safely disassembling the microwave. However, microwave capacitors store lethal voltage even when unplugged, so the repair requires discharging the capacitor before touching any internal components. If you are not experienced with microwave disassembly and capacitor discharge procedures, professional service is strongly recommended.

Unplugging the microwave for a few minutes may temporarily clear the error code, but C-20 will return as soon as the microwave attempts to use the temperature sensor again if the underlying fault has not been repaired. A reset does not fix a failed sensor, damaged wiring, or a loose connector. Persistent or recurring C-20 codes require physical inspection and repair.