Description & Operation: OBD-II

PCM detects malfunctions related to engine sensors or actuators. OBD-II continuously monitors emission related components and can store Diagnostic Trouble Codes (DTCs), 1st trip DTCs, freeze-frame data, 1st trip freeze-frame data and System Readiness Test (SRT) information. This data and DTC information can be retrieved to assist in diagnosing problems. Using the Malfunction Indicator Light (MIL) to access MIL codes is limited to code retrieval and fuel feedback monitoring, and is not recommended. It is recommended to use Generic Scan Tool (GST), or Nissan's CONSULT scan tool when performing self-diagnostic procedures, clearing PCM or performing a System Readiness Test (SRT).

When a malfunction is detected for the first time, the 1st trip DTC and 1st trip freeze frame data are stored in Powertrain Control Module (PCM) memory. However, in most instances, MIL will not be illuminated. If the same malfunction is detected on the next trip, MIL will be illuminated and a DTC is stored (2nd trip detection logic). If a misfire or fuel system malfunction should occur during 1st trip, MIL may be illuminated or flash. DTC and freeze-frame information will be stored to aid in diagnostics by specifying operating conditions when DTC was set.