The real meaning of the car engine P2661 Code is found from the manual of the car engine and the technician should follow the real meaning of the code for solving the car engine problem. If the real meaning of the code is not available, then he can use general meaning of the code for solving the car engine. The automobile dictionary meaning of the 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 1 for TFP Valve Position Switch-Drive Without Drive Ratio.