LG Heat Pump Error Code t5

The T5 code indicates an error with the oil temperature sensor in the outdoor unit of the heat pump. The system detects this fault when the outdoor temperature is above -10°C and the sensor signal voltage rises above 4.95V or drops below 0.5V, representing open-circuit or short-circuit conditions respectively. These limits correspond to temperature readings below -30°C or above 151°C, which are physically implausible under normal operating conditions. The control board flags the error to protect the compressor from operating without reliable oil temperature data.

It is not recommended to continue operating the heat pump while the T5 error is active. The oil temperature sensor protects the compressor by monitoring oil conditions, and running the system without a reliable sensor signal could allow the compressor to operate outside safe parameters. Continued operation risks compressor damage, which is a costly repair. Address the fault before resuming normal use.

Repair costs vary depending on the root cause. If only the sensor connector needs reseating, the cost may be limited to a service call fee, typically in the range of $75 to $150. Replacing the oil temperature sensor itself generally costs between $100 and $300 including parts and labor. If the outdoor unit control board has failed, the repair can range from $300 to $600 or more depending on parts availability and labor rates in your area.

A homeowner with basic electrical knowledge can check whether the sensor connector is fully seated on the PCB, which is the first recommended diagnostic step and requires no parts. However, measuring sensor resistance and comparing it to a resistance table, testing wiring continuity, and replacing the sensor or control board all require electrical testing tools and familiarity with the outdoor unit's components. If you are not comfortable working inside the outdoor unit, a qualified HVAC technician should handle the diagnosis and repair.

A power reset may temporarily clear the error code, but if the underlying fault with the oil temperature sensor, its wiring, or its connector is still present, the T5 code will return once the system restarts and attempts to read the sensor. Clearing the code without repairing the root cause does not protect the compressor. The fault should be diagnosed and corrected before relying on the unit for normal operation.