The meaning of the engine C1240 Code is necessary to know and getting the real meaning is not found from online. That is why, reading the manual of the car is necessary and general meaning of the code is available online. The general meaning of the engine code is C for Chassis Code Problem is controller area network wiring bus and modules. 1 for MFG – Manufacturer Specific. 2 for Accelerator Pedal Position (APP) Sensor 1 Performance. 4 for BBV Sensor Circuit Low Voltage and 0 for Transmission Engaged At High Throttle Angle. This engine code has a chassis problem and that is why, the code has started with C.