The B1666 Code is found while the car is diagnosis and it is necessary to solve the problem for running the car without any problem. If you have all machineries and manual, then you can solve the problem. The code is unidentifiable without knowing the manufacturer and model number. 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. 6 for Vehicle Speed Control and Idle Control System. 6 for Control Module Throttle Actuator Position Performance. 6 for Cruise Control System – Vehicle Accel Too High.