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Error code reference

LG Heat Pump Error Code E552

Low discharge pressure

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What the E552 error code actually means

Your LG heat pump is detecting that the pressure inside the refrigerant system is staying too low on the high-pressure side for too long, which means the system is not operating the way it should. This is often a sign that the system is low on refrigerant, has a blockage, or has an airflow problem at the outdoor unit. The heat pump has shut down to protect itself, and a technician will need to connect pressure gauges to diagnose the exact cause.

Diagnostic procedure

The full E552 procedure

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1
Confirm the fault
Power cycle the unit: switch off the breaker for 60 seconds, then restore power. If the code returns, the fault is persistent and the procedure below isolates the cause.
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Most common causes of E552

Ranked by how often they cause this code
  1. 1Low refrigerant charge
  2. 2Dirty or blocked condenser coil
  3. 3Condenser fan motor failure or reduced airflow
  4. 4Faulty or stuck expansion valve
  5. 5High-pressure sensor fault

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Questions people ask about E552

What does E552 mean on a LG heat_pump?
E552 indicates a low discharge pressure fault, meaning the high-side refrigerant pressure has remained at approximately 9 kg/cm² (about 128 psi) for 10 continuous minutes without rising to a normal operating level. This triggers a protective shutdown to prevent the system from running in a degraded condition. Common causes include low refrigerant charge, condenser airflow issues, or a faulty pressure sensor.
Is it safe to keep running my LG heat pump when E552 is active?
No, you should not continue operating the unit while this fault is active. The system shuts down specifically to protect the compressor and refrigerant circuit from damage caused by abnormal low-pressure conditions. Running the unit in this state risks compressor wear or failure, which is a much more costly repair.
Will resetting my LG heat pump clear the E552 error?
A power reset may temporarily clear the fault code and allow the unit to restart, but the code will return if the underlying problem has not been corrected. Because E552 requires sustained abnormal pressure conditions over 10 minutes to trigger, the fault indicates a real operating problem that reset alone will not resolve. Diagnosis and repair of the root cause are necessary for a lasting fix.
Can I fix E552 on my LG heat pump myself?
Some checks, like inspecting and cleaning the outdoor condenser coil or confirming the fan is spinning freely, can be done without special tools. However, diagnosing and correcting refrigerant-related causes requires manifold gauges and EPA Section 608 certification for refrigerant handling. If the system is low on refrigerant, a licensed HVAC technician must perform the leak search, repair, and recharge.
How much will it cost to repair an LG heat pump showing E552?
Repair costs depend heavily on the root cause. A coil cleaning or fan capacitor replacement may cost between $75 and $250 in parts and labor. A refrigerant leak search, repair, and recharge can range from $200 to $600 or more depending on the leak location and refrigerant type. A compressor replacement, if damage has already occurred, can run from $800 to over $2,000 including labor.

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