You need to fix the car engine for driving the car safely and the engine P0842 Code makes this easier. By the testing the car engine, you may get the engine code. You need to know the meaning of the code what is given by the car manufacturer. The automobile dictionary meaning of the code is p for Powertrain Code Problem is related engine, transmission and emissions systems. 0 for SAE – Generic. 8 for Ignition System Or Misfire 4 BBV Sensor Circuit Low Voltage. 2 for A/C System High Pressure High Temperature. You need to fix the car engine by the real meaning only.