The dictionary meaning of the P20D4 Code is found from online and it is easy to read but for solving the car engine problem, you should get the manufacturer information. The common meaning of the code is P for Powertrain Code Problem is related engine, transmission and emissions systems. 2 for MFG – Manufacturer Specific. 0 for Fuel And Air Metering. D for BBV Sensor Circuit Low Voltage and 4 for Cruise Vehicle Speed or Set Speed Difference Too High. The P20d4 engine code seems a type of powertrain problem. While use of fuel was enlarged, then acceleration was extremely bargained, and the loss of engine vacuum led to a unsafe loss of braking promotion when the P20d4 code system was in 4-cylinder mode.