Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
On Board Diagnostic Systems
California OBD-II applies to all gasoline engine vehicles up to 14, 000 lbs. Gross Vehicle Weight Rating (GVWR) starting in the 1996 MY and all diesel engine vehicles up to 14, 000 lbs. GVWR starting in the 1997 MY.
Several states in the northeastern United States have chosen to adopt the California emission regulations starting in the 1998 MY and are known as "Green States".
Green States receive California-certified vehicles for passenger cars and light trucks up to 6, 000 lbs. GVWR. Starting in the 2004 MY, Federal vehicle over 8, 500 lbs. will start phasing in OBD-II.
Starting in 2004 MY, gasoline-fueled medium duty passenger vehicles are required to have OBD-II. Federal OBD-II applies to all gasoline engine vehicles up to 8, 500 lbs. GVWR starting in the 1996 MY and all diesel engine vehicles up to 8, 500 lbs. GVWR starting in the 1997 MY.
OBD-II system implementation and operation is described in the remainder of this document.
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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.
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