The dictionary meaning of the B1921 Code is B for Body Code Problem is antilock brake system, electronic suspension and steering systems. 1 for MFG – Manufacturer Specific. 9 for Fuel and Air Metering. 2 for Air Conditioning (A/C) Clutch Feedback Circuit High Voltage and 1 for TFP Valve Position Switch-Drive Without Drive Ratio. Body of the engine has the fault and it is easy to solve. For solving the problem of the engine, you do not need to spend huge money. With least code, the problem from the engine can be solved. The manufacture changes the meaning of the code.