The engineer needs to solve the car engine problem and according to the car engineer, the meaning of the engine U1221 Code is necessary to know. For solving the car engine, getting the right meaning of the code and real cause are necessary to know. 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. 2 for BBV Sensor Circuit Low Voltage. 2 for BBV Sensor Circuit Low Voltage and 1 for Transmission. When the car engine is solved, then you may take it for a test drive.