LG Air Conditioner Error Code 43

Error code 43 on an LG air conditioner indicates a fault with the high pressure sensor in the outdoor unit. The control board has detected either an open circuit or a short circuit in the sensor signal path. The system typically shuts down when this code appears to prevent operation without valid pressure monitoring. A technician will need to inspect the sensor connector, wiring, and sensor itself to resolve the fault.

No, you should not attempt to run the unit while error code 43 is active. The high pressure sensor is a safety monitoring component, and operating the system without a valid pressure signal means the control board cannot detect a dangerous high pressure condition. Continued operation could risk damage to the compressor or other system components.

Resetting the unit by cutting power may temporarily clear the code, but it will return as soon as the PCB detects the open or short circuit condition in the sensor again. Error code 43 indicates an active electrical fault in the sensor circuit, not a one-time event, so a reset alone will not resolve the underlying problem. The sensor connection, wiring, and sensor itself must be inspected and repaired before the code will stay cleared.

The first step, checking that the sensor connector is properly seated on the outdoor PCB, is something a knowledgeable DIYer comfortable working around electrical components can perform safely with the unit powered down. However, testing sensor resistance and output voltage, replacing the sensor, or diagnosing PCB faults requires electrical testing skills and familiarity with refrigerant system components. If the connector check does not resolve the code, a certified technician should complete the diagnosis.

Repair costs depend on the root cause. If only a loose connector is found, a service call fee may be the primary cost, typically in the range of $75 to $150 depending on your area. If the high pressure sensor requires replacement, parts and labor combined generally fall in the range of $150 to $350. Outdoor PCB replacement is the most expensive scenario and can range from $300 to $600 or more including labor.