OBD-II Overview

The goal of the On Board Diagnostics-II (OBD-II) regulation, which was mandated by the Environmental Protection Agency (EPA), is to ensure proper emission system operation for the life of the vehicle by providing the vehicle with an "on-board" diagnostic system which is capable of continuously monitoring the efficiency of the emission control system.

To achieve this goal, OBD-II diagnostics monitors emissions-related components and systems for deterioration and identifies an emissions-related malfunction before the driver notices a problem with the vehicle.

The ECM illuminates the Malfunction Indicator Light (MIL) and stores a Diagnostic Trouble Code (DTC) for some failures in the Emissions System. The DTCs are retrieved using SST connected to the standardized OBD-II Data Link Connector (DLC) located below the left side of the instrument panel.

OBD-II diagnostics supports not only the standard test mode of OBD-II (Mode 01 -Mode 07) but also an advanced test Mode (Mode 22: Supported PID - analog inputs and outputs, digital inputs and outputs). All of these diagnostic test modes are supported using SST through the DLC.

The ECM executes the following key monitoring for OBD-II:

• Primary emission control system/components
• Heated oxygen sensors (includes heater)
• Catalyst
• Fuel system
• Evaporative emission system
• Misfire
• Comprehensive components (input and output)