Operation CHARM: Car repair manuals for everyone.
Hosted by mcallihan.com

On-Board Diagnostic (OBD) Test Description

ON-BOARD DIAGNOSTIC (OBD) TEST DESCRIPTION
The OBD Testing is divided into three special tests:
1 KEY ON ENGINE OFF (KOEO) SELF-TEST
2 KEY ON ENGINE RUNNING (KOER) SELF-TEST
3 CONTINUOUS MEMORY DTCS SELF-TEST

The OBD Tests 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, is usually performed at the start of each diagnostic procedure with all accessories off and is performed at end of most troubleshooting tests for verification of repair and make sure no other faults were incurred while servicing a previous fault.