The real meaning of the car engine P2666 Code is mostly useful but sometimes, you can easily and fast collect the automobile dictionary meaning from online. The general meaning of the car engine code is p for Powertrain Code Problem is related engine, transmission and emissions systems. 2 for MFG – Manufacturer Specific. 6 for Vehicle Speed Control And Idle Control System. 6 for Control Module Throttle Actuator Position Performance and 6 for Cruise Control System – Vehicle Accel Too High. This general meaning of the code may not match well with your car engine problem. That is why, you should look for the correct meaning of the code.