LG Air Conditioner Error Code E221

E221 indicates a fault with the outdoor ambient temperature sensor. The control board has detected a voltage signal from the sensor that is either above 4.9V, corresponding to a reading below -50°C and indicating an open circuit, or below 0.4V, corresponding to a reading above 93°C and indicating a short circuit. Both conditions are outside the valid operating range and trigger this error to protect the system.

Running the unit continuously while E221 is active is not advisable. The outdoor temperature sensor input is used by the control board to manage compressor operation and refrigerant pressures. Without a valid reading, the system may operate outside safe parameters, which can shorten compressor life or cause additional component failures. Power the unit off until the sensor circuit is repaired.

Repair costs vary depending on what has failed. If only the outdoor temperature sensor thermistor needs replacement, parts and labor typically range from around $75 to $200 depending on the model and local labor rates. If the outdoor control board is also damaged, total costs can range from $200 to $500 or more. Getting a diagnostic visit from a qualified technician will give you a more accurate estimate for your specific unit.

A knowledgeable DIYer can inspect the sensor wiring and connectors for visible damage or corrosion without specialized tools. Measuring sensor resistance with a multimeter is also straightforward. However, if the thermistor or control board needs replacement, and especially if the system uses refrigerant circuits that must be accessed, a certified technician is recommended to complete the repair safely and correctly.

A power reset may temporarily clear the error display, but E221 will return as soon as the control board re-reads the out-of-range voltage from the faulty sensor circuit. The underlying problem, whether a failed thermistor, damaged wiring, or a bad connector, must be physically corrected before the error will clear permanently.