Smoke Opacity Testing

Why California is Inspecting Heavy-Duty Vehicles

Only two percent of California’s vehicles are heavy-duty vehicles, but they produce about 30 percent of nitrogen oxides (a key smog forming compound) and about 65 percent of soot emissions from motor vehicles. Smog and airborne soot can cause or aggravate many kinds of respiratory problems.

Heavy-Duty vehicle owners can do their part to improve air quality by preventing excessive emissions from their equipment. Proper vehicle maintenance reduces emissions and saves money! The inspections ensure that all vehicles operating in California meet reasonable standards of maintenance and help protect the air we all breathe.

The Common Cause of Excessive Smoke

Poorly maintained engines emit excessive smoke. The best way to pass the test is to properly maintain your engine. Common Maintenance problems are:

• Smoke puff limiters
• Max fuel rate too high
• Fuel pump calibration
• Fuel injection timing
• Allowable Levels of Smoke Opacity

All 1991 or newer engines:

must not exceed 40 percent smoke opacity.

All pre-1991 engines:

must not exceed 55 percent smoke opacity.

The Penalties for Excessive Smoke are:

Notice of Violation:

For pre-1991 vehicles that have smoke opacities greater than55 percent but less than 70 percent and have not received a citation in the past 12 months a Notice of Violation is issued. Similar to a "fix-it Ticket", the Notice of Violation has no penalty if repairs are made to the engine and a Demonstration of Correction form is submitted to the ARB (Air Resource Board) within 45 days. If repairs are not made and a Demonstration of Correction form is not submitted within 45 days, a citation will be issued. Only one Notice of Violation mat be issued to a vehicle within a 12 month period.

First Level Citation:

For ore-1991 engines with 70 percent or greater smoke opacity and 1991 and newer engines with greater than 40 percent opacity, that have not received any citations in the past 12 months a First Level Citation is issued. The penalty for a First Level Citation is $300 if engine repairs are made and a Demonstration of Correction form is not submitted to the ARB within 45 days.

The penalty is increased to $800 if repairs are no made and a Demonstration of Correction form is not submitted with the ARB within 45 days.

Second Level Citation:

The Penalty for any further violations within a 12 month period is $1800. In addition, a Demonstration of Corrections for must be submitted and the vehicle must be retested by the ARB in order to clear the citation.

In extreme cases, the CHP may take a vehicle out of service for an outstanding citation if the penalty has not been paid, or if the vehicle has not been repaired.

The best way to avoid a citation is to properly maintain your engine!