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)

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

OBD-II Overview

Use the Manual With the Right Hardware

When to See a Mechanic