The B1594 Code is related with the car engine and you will get code when the car engine is checking by machineries. There are many expensive tools and machineries available for solving the problem and checking. For solving the engine problem, there are some information and manual is necessary. If you do not say the model number and manufacturer name, the definition of the meaning of the code remains unknown. You have to know the meaning of the code and the dictionary meaning of the code is B for Body Code Problem is antilock brake system, electronic suspension and steering systems. 1 for MFG – Manufacturer Specific. 5 for Computer and Auxiliary Outputs. 9 mean Crankshaft Position Sensor Circuit Performance and 4 means Cruise Vehicle Speed Difference Too High.