The engine C1840 Code has automobile meaning and it is also known as general meaning. The automobile meaning of the engine code is C for Chassis Code Problem is controller area network wiring bus and modules. 1 for MFG – Manufacturer Specific. 8 for Ignition System Or Misfire. 4 for BBV Sensor Circuit Low Voltage and 0 for Transmission Engaged At High Throttle Angle. However, you need to use this general meaning of the code for learning general thing of the car engine code. If you want to fix the car engine, you need to know the correct meaning of the code.