Trane Furnace Error Code ERR 119

ERR 119 indicates that temperature sensor 1 or temperature sensor 2 has been detected as either shorted (near-zero resistance) or open circuit (very high or infinite resistance). These sensors monitor thermal conditions inside the furnace to ensure safe burner and blower operation. When the control board cannot get a valid reading from a sensor, it triggers ERR 119 and typically halts the heating cycle. The fault points to a failed sensor, damaged wiring, or a faulty connector.

Operating the furnace with a temperature sensor fault is not recommended. The sensor exists to give the control board accurate thermal data so it can prevent overheating and unsafe heat exchanger conditions. Without reliable sensor input, the furnace cannot properly protect itself or your home. Most Trane furnaces will lock out heating operation when ERR 119 is active, so the unit may not run at all until the fault is resolved.

Repair costs vary depending on what is causing the fault. A simple connector cleaning or re-seating may cost only a service call fee, typically in the range of $75 to $150. Replacing a temperature sensor usually adds parts costs of roughly $20 to $80 depending on the specific sensor required. If the control board is at fault, board replacement can run between $200 and $600 or more for parts alone, plus labor.

A knowledgeable DIYer can inspect wiring and connectors for visible damage, corrosion, or loose connections and address those issues. Testing the thermistor with a multimeter to check for an open or short is also within reach if you have basic electrical troubleshooting skills. However, replacing a temperature sensor or control board involves working inside the furnace cabinet and requires comfort with electrical components, so many homeowners prefer to call a qualified technician for this repair.

A reset may temporarily clear the error code, but if the underlying sensor, wiring, or connector fault still exists, ERR 119 will return once the furnace attempts to operate and checks the sensor again. Resetting without diagnosing the root cause is not a lasting solution. The fault needs to be traced to the specific sensor or wiring issue and repaired before the error will stay cleared.