LG Air Conditioner Error Code 203

Error code 203 indicates an abnormal signal from the sub-cooling discharge pipe temperature sensor in the HR unit. The control board has detected either an open circuit or a short circuit condition on that sensor circuit. The system cannot reliably monitor refrigerant temperature at that point, so it stops operating to prevent damage. The sensor, its wiring, and connector should be inspected and tested to find the cause.

You should not attempt to bypass or ignore error code 203. The sub-cooling discharge pipe temperature sensor provides data the system needs to manage refrigerant conditions safely. Running the system without a valid sensor reading could result in undetected over-temperature conditions and potential damage to the HR unit's refrigerant circuit or compressor.

A power reset may temporarily clear the error code from the display, but if the underlying sensor or wiring fault is still present, the code will return once the system restarts and attempts to read the sensor. A reset does not repair a failed thermistor, broken wire, or corroded connector. The root cause must be identified and corrected for the error to clear permanently.

A knowledgeable DIYer can start by checking whether the sensor connector is fully seated and whether the lead cable shows any obvious physical damage. However, testing sensor resistance accurately requires a multimeter and familiarity with thermistor resistance curves. Work inside the HR unit also involves proximity to refrigerant components and high-voltage wiring, so a qualified technician is recommended for anything beyond a basic visual inspection.

If the fix is simply reseating a loose connector, the cost is limited to a service call fee, typically in the range of $75 to $150. Replacing the temperature sensor itself generally adds $20 to $80 in parts cost plus labor. If the lead cable or control board requires replacement, total repair costs can range from $200 to $600 or more depending on parts availability and labor rates in your area.