The automobile meaning of the engine U1900 Code is not very helpful thing and it is necessary to know the real meaning for the automobile engineer for solving the car engine problem. The automobile meaning of the engine code is U for Network Code Problem is climate control system, lighting, airbags, etc. 1 for MFG – Manufacturer Specific. 9 for Fuel And Air Metering or Injector Circuit Malfunctions Only. 0 for IC Circuit High Voltage and 0 for Transmission Engaged At High Throttle Angle. The real meaning of the code is similar to the general meaning but you should not fix the car engine without the real meaning of the code.