LG Heat Pump Error Code t1

The T1 code indicates a fault with the outdoor ambient temperature sensor. The outdoor PCB monitors the sensor's signal voltage and triggers this error when that voltage exceeds 4.9V (open circuit, corresponding to -50°C) or drops below 0.4V (short circuit, corresponding to 93°C). Either condition tells the board that the sensor cannot be providing a valid temperature reading, so the unit shuts down to protect itself.

The heat pump will generally not continue normal operation once T1 is active, as the unit locks out to prevent running the compressor without valid outdoor temperature data. Attempting to force operation without resolving the fault could lead to inefficient cycling or component stress. It is best to address the sensor fault before returning the unit to regular use.

A power reset may temporarily clear the T1 error code, but the fault will return as soon as the outdoor PCB reads the sensor signal again if the underlying problem has not been fixed. Resetting the unit without repairing the sensor or wiring is not a lasting solution. The error should be diagnosed and corrected before the unit is returned to service.

Some causes of the T1 error are accessible to a knowledgeable DIYer. Checking whether the sensor connector is fully seated at the outdoor PCB and inspecting the wiring harness for visible damage are reasonable first steps. However, measuring sensor resistance and comparing it against the resistance table requires a multimeter and some familiarity with reading electrical specifications. Replacing the sensor or PCB is best handled by a qualified technician, especially since the outdoor unit involves refrigerant-side components and line voltage.

If only the outdoor temperature sensor needs replacement, parts and labor typically fall in the range of $75 to $200 depending on your region and the specific model. If the connector or wiring harness is the issue and no parts are needed, a service call alone may be the primary cost. Control board replacement, if required, can raise the total to a range of $300 to $600 or more.