LG Refrigerator Error Code aS

The aS code on an LG refrigerator indicates a failure in the ambient room temperature sensor circuit. The control board has detected either a short circuit (0V at POINT F) or an open circuit (5V at POINT F) in the sensor loop. This sensor helps the refrigerator adjust its operation based on the surrounding environment, so this fault can affect overall cooling performance if left unresolved.

The aS code is not a safety hazard in the traditional sense, and the refrigerator may continue to cool to some degree. However, without accurate ambient temperature data, the control board cannot optimize compressor and fan cycling correctly, which can reduce efficiency and potentially affect food preservation over time. It is best to address the fault promptly rather than relying on the appliance while the sensor circuit is compromised.

Repair costs depend on which component has failed. A replacement ambient temperature thermistor sensor typically costs between $15 and $50 for the part alone. If professional labor is included, or if the wiring harness or control board requires replacement, total repair costs can range from $100 to $350 or more depending on your location and the specific parts needed.

A knowledgeable DIYer can start by checking the sensor's harness connector for loose pins, corrosion, or obvious wire damage, which sometimes resolves the issue without parts. If the connector looks intact, testing the thermistor's resistance with a multimeter and comparing it to expected values for room temperature can confirm whether the sensor itself has failed. Replacing the ambient sensor is a relatively straightforward repair, but if the wiring or control board is involved, professional diagnosis is recommended.

A power reset may temporarily clear the aS code from the display, but the code will return if the underlying sensor circuit fault is still present. Because the control board continuously monitors the sensor, any persistent short or open condition will trigger the code again within a short time after restart. A reset is useful for confirming whether the fault is intermittent, but it does not substitute for proper diagnosis and repair.