LG Heat Pump Error Code E425

E425 indicates a low pressure sensor error detected while the compressor is preparing to start. The control board found the sensor signal voltage was either below 0.4V, indicating a SHORT, or above 4.7V, indicating an OPEN circuit. The system shuts down to protect the compressor until the sensor circuit is restored to a valid operating range.

No. The E425 fault locks out the compressor specifically to prevent it from operating without valid pressure sensor feedback. Running the system in this condition could result in compressor damage. Leave the unit off until the sensor circuit is inspected and repaired.

A reset may temporarily clear the fault code, but E425 will return as soon as the system attempts to start the compressor again if the underlying wiring or sensor problem has not been fixed. A reset is useful for confirming whether the fault is intermittent, but it is not a repair. The sensor circuit must be inspected and corrected to permanently clear the error.

A homeowner comfortable with basic electrical inspection can start by checking the sensor's wiring connector for looseness, corrosion, or visible damage. If the connector is secure and the wiring looks intact, diagnosing further requires a multimeter to measure sensor voltage, and any refrigerant-related work must be done by a certified technician. Replacing the sensor itself is a moderate repair that many experienced DIYers can handle, but accessing refrigerant lines should always be left to a professional.

If the fix is simply reseating a connector or repairing a damaged wire, costs are minimal, typically in the range of $50 to $150 for a service call. If the low pressure sensor needs replacement, parts and labor generally run $150 to $400 depending on the model and your location. A control board replacement, if required, can push costs to $400 to $800 or more.