Common OBD-II Terms: Diagnostic

The word "diagnostic" refers to any on-board test run by the vehicles Diagnostic Management System. A diagnostic is simply a test run on a system or component to determine if the system or component is operating according to specification. There are many diagnostics as shown in following list:

• Misfire
• Oxygen Sensors
• Oxygen Sensor Heaters
• EGR
• Catalyst Monitoring