Diagnostic Trouble Codes
Modern vehicles are equipped with a diagnostic system known as On-Board Diagnostics II (OBD II). This system monitors operation and function of all engine management systems and automatic transmission operation to insure correct emission levels.

If a malfunction occurs, a Check Engine Light will alert the driver whom must scan the system for stored fault codes. These fault codes are known as Diagnostic Trouble Codes (DTCs), which are used to identify possible problem areas and specific failed components.