Common Terms: Diagnostic: Notes

When used as a noun, the word diagnostic refers to any on-board test run by the vehicle's 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, shown in the following list:

• Misfire
• Front heated oxygen sensor (HO2S1)
• Rear heated oxygen sensor (HO2S2)
• Exhaust gas recirculation (EGR)
• Catalyst monitoring
• Fuel system