You can follow automobile dictionary meaning of the car engine P1304 Code and it is p for Powertrain Code Problem is related engine, transmission and emissions systems. 1 for MFG – Manufacturer Specific. 3 for IC Module 4X Ref Circuit Intermittent, No Pulses. 0 for IC Circuit High Voltage and 4 for Cruise Vehicle Speed/Set Speed Difference Too High. The P1304 error code seems a kind of powertrain problem and this problem should be fixed properly by real meaning of the car engine but when you have no the right meaning of the code, you can use the automobile dictionary meaning of the code.