Before driving the car, you must fix the car engine if you find any trouble in the car engine. Because for the car engine’s problem, you may make accident. The engine P0840 Code is very important and meaningful. Do not use any meaning of the code except the real one. 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 for BBV Sensor Circuit Low Voltage and 0 for Transmission Engaged At High Throttle Angle. You will learn general information form here.