OBD-II Subaru Diagnostic Systems:
The following is a brief description of the Subaru OBD-II system:
• The Subaru on-board diagnostic (OBD-II) system has the ability to detect and indicate faults in various inputs and outputs of the vehicle’s electronic control systems. A CHECK ENGINE malfunction indicator lamp (MIL) in the combination meter indicates the occurrence of a fault or trouble.
• A fail-safe function is provided to ensure minimal drive-ability in the event of a failure of a component or sensor that may disable the electronic control system.
• The OBD-II system incorporated in all Subaru vehicles since 1996 complies with Section 1968.1 of the California Code of Regulations (OBD-II regulation), and all applicable Federal Clean Air Act regulations. The OBD-II system monitors components and system malfunctions which may have an effect on emissions.
• When the system decides that a malfunction has occurred, the MIL illuminates. At the same time that the MIL illuminates or blinks, a diagnostic trouble code (DTC) and freeze frame data of engine conditions are stored in the on-board computer’s memory.
• When it detects a malfunction, the OBD-II system stores freeze frame engine condition data (engine load, engine coolant temperature, fuel trim, engine speed and vehicle speed, etc.) into the on-board computer memory.
• If the OBD-II system detects various malfunctions, including a fuel trim fault or misfire, the OBD-II system first stores freeze frame engine conditions about the fuel trim or misfire.
• If the malfunction does not occur again for three “trips,” the MIL turns off, but the DTC remains in the on-board computer’s memory.
• The OBD-II system is capable of communication with a generic scan tool (OBD-II generic scan tool), defined by ISO 9141 CARB specifications.
• The OBD-II diagnostic procedure is different from the usual diagnostic procedure. When troubleshooting Subaru OBD-II vehicles, it is necessary to connect a Subaru Select Monitor or New Select Monitor to the vehicle. If these tools are not available, a generic OBD-II scan tool may also be used.
