Introduction to On Board Diagnostics (II)

Introduction to On BoardDiagnostics (II)Specific “Freeze Frame” diagnostic data must be stored whenthe first malfunction is detected. If a second malfunction in thefuel system or misfire function occurs, then the first data mustbe replaced with the subsequent malfunction data. Diagnosticdata must be made available when requested by the Scan tool.Results of the most recent tests and limits to which those resultsare compared with, must be made available for all emissioncontrol systems, for which OBD II diagnostics are conducted.The message content and down loading protocol is defined forall fault codes, specific data values, and “Freeze Frame” data.