LG Range Error Code E-27

Error code E-27 on an LG range indicates that the oven temperature sensor has developed an open circuit condition. The control board monitors the resistance of the oven temperature sensor (also called an RTD sensor or oven thermistor) continuously during operation. When the resistance reading exceeds 40,000 ohms, the board interprets this as a broken or disconnected circuit and triggers E-27. Under normal conditions, the sensor should read approximately 1,080 ohms at room temperature, rising predictably as oven temperature increases. A reading above 40K ohms is far outside the acceptable operating range and means the board cannot determine actual oven temperature, making safe operation impossible.

The oven temperature sensor is a probe mounted inside the oven cavity, typically secured to the rear wall, with wiring routed through the back of the range to the control board. An open circuit in this system can result from a physically broken sensor element, a severed or corroded wire in the sensor harness, or a connector that has become loose or burned. The sensor element itself can crack or fail due to prolonged heat exposure or a sudden thermal shock, such as contact with cold liquid during a self-clean cycle. Wiring damage is also common when harness wires are routed near sharp metal edges or heat sources.

Diagnosis begins with disconnecting power to the range and removing the upper rear cover panel to access the sensor and its wiring. Using a multimeter set to the ohms setting, measure resistance directly across the sensor terminals. A properly functioning sensor will read close to 1,080 ohms at room temperature. Any reading significantly above this, or an open circuit reading (OL or infinite resistance), confirms the sensor has failed and requires replacement.