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Error code reference

LG Air Conditioner Error Code 209

HR unit 3 liquid pipe temperature sensor error (open or short).

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What the 209 error code actually means

Your LG air conditioning system has detected a problem with a temperature sensor located on the liquid refrigerant pipe in one of its heat recovery units. The system cannot read a valid temperature from that sensor, so it has shut down to protect itself from potential damage. A technician will need to inspect the sensor wiring and the sensor itself to find and fix the issue.

Diagnostic procedure

The full 209 procedure

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First diagnostic step
Check connection condition of temperature sensor and lead cable.
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Most common causes of 209

Ranked by how often they cause this code
  1. 1Loose or disconnected sensor connector
  2. 2Failed NTC thermistor sensor
  3. 3Damaged lead cable or wiring
  4. 4Corrosion at terminal pins
  5. 5Control board sensor input fault

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Questions people ask about 209

What does 209 mean on a LG air_conditioner?
Error code 209 on an LG air conditioner signals a fault with the HR unit 3 liquid pipe temperature sensor. The control board has detected either an open circuit or a short circuit in that sensor's signal, meaning the resistance value is outside the valid range. The system shuts down to prevent unsafe operation without accurate refrigerant temperature data.
Is it safe to keep running my LG air conditioner with error code 209 active?
No. The system has faulted and shut down specifically because it cannot monitor the liquid pipe temperature in HR unit 3. Attempting to bypass or force the system to operate without a functioning sensor could result in improper refrigerant flow, potential compressor damage, or other system failures. The fault should be resolved before resuming normal operation.
Will resetting my LG air conditioner clear error code 209?
A power reset may temporarily clear the fault code, but if the underlying sensor, connector, or wiring issue is still present, the error will return as soon as the system attempts to read the sensor again. The root cause must be diagnosed and corrected before the code will clear permanently.
Can I fix error code 209 on my LG air conditioner myself?
Some basic checks, such as inspecting the sensor connector and reseating it, can be performed without specialized tools. However, testing the thermistor resistance, tracing wiring faults, and replacing components in a VRF or multi-zone HR system typically requires a qualified HVAC technician with the appropriate equipment and knowledge of refrigerant systems.
How much does it cost to repair error code 209 on an LG air conditioner?
Repair costs depend on the root cause. If only a loose connector needs to be reseated, labor costs may be minimal, typically in the range of $75 to $150 for a service call. If the thermistor sensor itself needs replacement, parts and labor combined could run $150 to $400 or more. Control board replacement, if required, would be at the higher end of the cost range.

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