LG Heat Pump Error Code E277

E277 indicates a high pressure sensor breakaway fault. The control board has detected that the high pressure sensor signal is absent or outside its valid range, pointing to a wiring, connector, or sensor failure rather than an actual refrigerant over-pressure event. The system shuts down to prevent unmonitored operation of the refrigerant circuit.

No. The E277 fault causes the heat pump to shut down because the control board can no longer monitor high-side refrigerant pressure. Operating the system without a functioning high pressure sensor could allow dangerous over-pressure conditions to go undetected, potentially damaging the compressor or other refrigerant circuit components. Keep the unit off until the fault is resolved.

Repair costs depend on the root cause. A simple connector reconnection during a service call might cost between $75 and $150 in labor. Replacing a high pressure sensor typically ranges from $100 to $300 including parts and labor. If the main control board is at fault, costs can range from $300 to $700 or more depending on the specific model and board availability.

A homeowner can safely check for an obvious disconnected or loose connector at the high pressure sensor without working on the refrigerant system. However, tracing wiring faults, testing sensor output, or replacing refrigerant-circuit components requires proper tools and, in most regions, certification to handle refrigerants. It is recommended to contact a licensed HVAC technician for a full diagnosis.

A power reset may temporarily clear the fault display, but the error will return as soon as the control board attempts to read the high pressure sensor signal again. The underlying cause, whether a loose connector, damaged wire, or failed sensor, must be physically repaired before the fault will clear permanently.