The general meaning of the P20C4 Code is found for the car engine. The general 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. C for BBV Sensor Circuit Low Voltage and 4 for Cruise Vehicle Speed/Set Speed Difference Too High. While the fuel economy was improved, the acceleration was very negotiated, and the loss of engine vacuum led to a dangerous loss of braking assist when the P20c4 code system was in four-cylinder mode. It is easy to solve the problem.