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Error code reference

LG Heat Pump Error Code E471

Outdoor unit compression rate 1 error (compression ratio over 8.5 for more than 5 minutes).

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What the E471 error code actually means

Your LG heat pump has detected that the pressure difference inside the outdoor unit's compressor has gotten too high and stayed that way for too long, which puts the system under serious strain. This usually means something is restricting refrigerant from flowing properly, such as a valve that is not fully open or a low refrigerant level. A technician will need to check the system pressures and refrigerant charge to find and fix the cause.

Diagnostic procedure

The full E471 procedure

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First diagnostic step
Check service valves; check PWM valve; check refrigerant charge.
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Most common causes of E471

Ranked by how often they cause this code
  1. 1Closed or partially closed service valve
  2. 2Low refrigerant charge
  3. 3Faulty or stuck PWM expansion valve
  4. 4Refrigerant leak
  5. 5Blocked or restricted outdoor coil

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Questions people ask about E471

What does E471 mean on a LG heat pump?
E471 means the outdoor unit's compression ratio has exceeded 8.5 and remained at that level for more than 5 minutes. The compression ratio is the relationship between high-side discharge pressure and low-side suction pressure. When this ratio stays too high, the compressor is under abnormal stress. The most likely causes are a closed service valve, low refrigerant charge, or a malfunctioning PWM expansion valve.
Is it safe to keep running my LG heat pump with an E471 error?
Continuing to operate the system with an E471 error is not recommended. A sustained compression ratio above 8.5 places the compressor under significant mechanical and thermal stress, which can lead to compressor damage or failure if the underlying cause is not corrected promptly. Shut the unit down and have a technician inspect it before resuming normal operation.
How much does it cost to repair an E471 error on an LG heat pump?
Repair costs depend on the root cause. If the fix is simply opening a closed service valve or cleaning a blocked coil, the cost may be limited to a service call fee, typically in the range of $75 to $150. If a refrigerant leak and recharge are needed, costs generally range from $200 to $600 depending on refrigerant type and leak severity. Replacing a PWM expansion valve can add $150 to $400 or more in parts and labor.
Can I fix E471 on my LG heat pump myself?
One step a homeowner can safely take is confirming that the service valves on the outdoor unit are fully open, since a partially closed valve is a common cause of this error. Beyond that, diagnosing refrigerant charge and PWM valve operation requires manifold gauges and EPA certification to handle refrigerant, so those steps should be performed by a qualified HVAC technician.
Will resetting my LG heat pump clear the E471 error?
A power reset may temporarily clear the error code, but E471 will return if the underlying issue is not resolved. The fault is triggered by a sustained pressure condition, not a one-time sensor spike, so resetting without correcting the root cause will not fix the problem. Address the service valves, refrigerant charge, and PWM valve before expecting the code to stay cleared.

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