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. When the system reads an error, a Diagnostic Trouble Code (DTC) will be generated.

After pulling your DTC with either a scan tool or onboard diagnostics, lookup the actual code definition within ALLDATAdiy.com and follow the repair process.