The engine C1243 Code is actually vital thing and receiving the right meaning of the code is needed to know. Do not follow general meaning for cracking the car engine problem. Read the car manual where you will get some information what help you to find the real meaning of the car engine code. The automobile dictionary meaning of the 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 Sensor. 1 for Performance. 4 for BBV Sensor Circuit Low Voltage and 3 for Transmission Control Module Reprogrammable Memory.