On-Board Diagnostics

The On-Board Diagnostics (OBD) system detects and indicates a fault in various inputs and outputs of the complex electronic control system. "CHECK ENGINE" malfunction indicator lamp (MIL) in the combination meter indicates occurrence of a fault or trouble.

To further guard against a failure of sensors which may disable the driveability of the vehicle, the fail-safe function is provided to ensure that minimal driveabilty is retained should such a fault occur.

The OBD system incorporated with the vehicles within this engine family complies with Section 1968.1, California Code of Regulations (OBD-I I regulation).

When the system decides, that a malfunction occurs, MIL illuminates. At the same time of the MIL illumination or blinking, a diagnostic trouble code (DTC) and freeze frame engine conditions are stored into the on-board computer.

The OBD system stores freeze frame engine condition data (engine load, engine coolant temperature, fuel trim, engine speed and vehicle speed, etc.) into on-board computer when it detects a malfunction first.

If the OBD system detects the various malfunctions including the fault of fuel trim or misfire, the OBD system first stores freeze frame engine conditions about the fuel trim or misfire.

When the malfunction does not occur again for three consecutive driving cycles, MIL is turned "OFF", but DTC remains in the on-board computer.

The OBD-II system is capable of communication with a general scan tool (OBD-II general scan tool) formed by ISO 9141 CARB.

The OBD-II diagnostics procedure is different from the usual diagnostics procedure. When troubleshooting OBD-II vehicles, connect Subaru Select Monitor or the OBD-II general scan tool to the vehicle.