The meaning of the P20AF Code is common as general meaning but for solving the engine problem the manufacturer meaning is necessary. You should get the manufacturer’s meaning about the code of the car engine. The dictionary meaning of this P20AF code is available online but you should not follow the dictionary meaning for solving the car engine. The dictionary meaning of the code is P for Powertrain Code – Problem is related engine, transmission and emissions systems. 2 for MFG – Manufacturer Specific. 0 for Transmission. A for BBV Sensor Circuit Low Voltage and F for TFP Valve Position Switch-Drive Without Drive Ratio.