On-Board Diagnostic (OBD) Test Description

The On-Board Diagnostic (OBD) Test is divided into three special tests: Key On Engine Oft Self-Test (KOEO), Key ON, Engine Running (KOER) Self-Test and Continuous Memory DTCs Self-Test. The OBD test checks the integrity and function of the powertrain control system and outputs the test results when requested by the NGS Tester. It also provides a quick end check of the powertrain control system. It is usually performed at the start of each diagnostic procedure with all the accessories off and is performed at the end of most troubleshooting tests for verification of repair and to make sure no other faults were incurred while servicing a previous fault.