The automobile dictionary meaning of the U1239 code is U for OBD-II Diagnostic Powertrain (U) Trouble Code For Engine. 1 for Intake Valve Control Solenoid Circuit Low. 2 for Engine Oil Temperature Sensor Malfunction. 3 for Cylinder 10 Contribution/balance Fault and 9 for Reverse Input Circuit. The engine U1239 Code helps you to solve the car engine if the right meaning of the code is found. The automobile dictionary meaning of the code may not support the car engineer for solving the car engine. You will get more information if you study the correct meaning what is found from the car manufacturer.