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Error code reference

LG Heat Pump Error Code E404

Outdoor unit overload 1 protection control error.

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What the E404 error code actually means

Your LG heat pump has detected that the outdoor unit is working too hard and getting too hot or drawing too much electrical current, so it shut itself down to prevent serious damage. This is a protective response, not a sudden failure, but it does mean something is causing the outdoor unit to be overloaded. A technician will need to check the unit's airflow, refrigerant levels, and electrical supply to find the root cause.

Diagnostic procedure

The full E404 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 E404

Ranked by how often they cause this code
  1. 1Dirty or blocked condenser coil
  2. 2Incorrect refrigerant charge
  3. 3Failing or weak compressor
  4. 4Low or imbalanced supply voltage
  5. 5Faulty overload sensor or control board

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Questions people ask about E404

What does E404 mean on a LG heat_pump?
E404 indicates an outdoor unit overload protection control error on your LG heat pump. The system has detected that the outdoor unit compressor or its associated circuit is experiencing excessive current draw or thermal stress. The unit shuts down to prevent compressor damage, and the fault code is stored so a technician can diagnose the root cause.
Will resetting the unit clear the E404 code?
Resetting the unit may temporarily clear the E404 code and allow the heat pump to restart, but if the underlying cause is not resolved, the error will return quickly. A reset is useful for ruling out a one-time electrical anomaly, but repeated E404 faults after reset indicate a real mechanical or electrical problem that needs professional diagnosis.
How much does it cost to repair an E404 error on an LG heat pump?
Repair costs vary widely depending on the cause. A condenser coil cleaning or refrigerant recharge typically runs in the range of $150 to $400. If the compressor itself has failed, replacement costs can range from $800 to $2,500 or more depending on the unit size and labor rates in your area. Getting a diagnostic visit first will help identify the specific cause before committing to a repair cost.
Can I fix the E404 error myself?
Some basic checks are within reach for a knowledgeable homeowner, such as clearing debris from around the outdoor unit and cleaning a visibly dirty condenser coil. However, diagnosing refrigerant charge issues, measuring compressor amperage, and testing electrical supply requires proper equipment and training. Most E404 repairs will need a licensed HVAC technician to complete safely and correctly.
Is it safe to keep running my heat pump when E404 is displayed?
You should not continue running the unit while E404 is active. The error code means the system's protection controls have detected an overload condition and shut down the outdoor unit specifically to prevent compressor damage. Attempting to force the unit to run through repeated resets without fixing the underlying cause risks permanent compressor failure, which is a much more costly repair.

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