This SAE Recommended Practice supersedes SAE J2012 MAR1999, and is technically equivalent to ISO/DIS 15031-6:April 30, 2002. This document is intended to define the standardized Diagnostic Trouble Codes (DTC) that On-Board Diagnostic (OBD) systems in vehicles are required to report when malfunctions are detected. This document includes:

1. a Diagnostic Trouble Code format
2. b A standardized set of Diagnostic Trouble Codes and descriptions