The engine U1234 Code plays import role for solving the car engine. The right meaning of the code is used most for solving the car engine. The real meaning of the engine code is found from the car manufacturers. The automobile code’s general meaning is U for Network Code Problem is climate control system, lighting, airbags, etc. 1 for MFG – Manufacturer Specific. 2 for Accelerator Pedal Position (APP) Sensor 1 Performance. 3 for Cruise Control Servo Indicates Low and 4 for Cruise Vehicle Speed/Set Speed Difference Too High. Do not drive the car with the engine problem and you should fix it properly.