The OBD II system uses a Diagnostic Trouble Code (DTC) identification system established by the Society of Automotive Engineers (SAE) and the EPA. The codes are a standardized set of identifiers used to help pinpoint the location of a fault within the on-board electronic controls systems.
The first letter of the DTC is used to identify the type of computer system that has failed. This letter will be followed by 4 numbers, the letters are described as shown below:
The first DTC number indicates a generic (P0XXX) or manufacturer (P1XXX) type code. A list of trouble codes is included in this section.