The automobile dictionary meaning of the car engine P2318 Code is p for Powertrain Code Problem is related engine, transmission and emissions systems. 2 for MFG – Manufacturer Specific. 3 is IC Module 4X Ref Circuit Intermittent, No Pulses. 1 for Low Coolant Circuit and 8 for PCM Stack Overrun. This car engine code’s meaning is common for all car engine codes but the problem of the car engine may not be similar. You need to test the car engine and need the right meaning of the code for solving the car engine as soon as possible. Do not try to fix the car engine if you are not a right person to do so.