VW Diagnostic Trouble Codes (DTC)
From model year 1996, vehicles manufactured for the North American market are equipped with a Government required diagnostic system known as On-Board Diagnostics II (OBD II). This system monitors operation and function of all engine management system activity and automatic transmission operation to insure compliance with specified emission levels.
Vehicle emission levels are constantly monitored by the OBD II system and malfunctions are recognized and recorded. A Malfunction Indicator Light (MIL) in the instrument cluster alerts the driver to the fault and the need to have the system checked for fault codes. These codes follow a standard format and are known as Diagnostic Trouble Codes (DTCs).
DTCs are assigned two codes. The first code is a numerical code assigned by the factory. The second code is referred to as a P-code and follows a structure required by law and defined by the Society of Automotive Engineers (SAE). This standard uses a letter to designate the system and four numbers to further identify and detail the malfunction as listed below.
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