Massachusetts is one of the many states that requires a regular emission inspection for most vehicles. This is necessary because the combustion of fossil fuels (such as gasoline and diesel fuel) within the engine results in pollutants, such as nitrogen oxides, carbon monoxide, sulfur dioxide, carbon dioxide, and other hazardous gasses and particulates that are released into the air each time you drive.
Although no system can eliminate these pollutants completely, all new vehicles are equipped with emission control systems, which significantly reduce them, resulting in cleaner air, less smog and soot, and fewer airborne particulates, which can cause respiratory problems with prolonged exposure. In states with dense urban areas and a large number of vehicles on the road, such as Massachusetts, it’s essential that these systems remain functioning optimally, which is why the state requires the following annual tests:
- On-Board Diagnostic Test
This test inspects the data collected by your vehicle’s onboard computer. It typically takes less than five minutes as is required for model year 2000 and newer passenger and light-duty diesel vehicles, 2008 and newer medium-duty vehicles, and 2007 and newer medium-duty diesel vehicles.
- Snap Acceleration Opacity Test
This test measures the opacity of the exhaust smoke and is required for medium-duty and heavy-duty diesel vehicles that do not have on-board diagnostic systems. The higher the smoke’s opacity, the more pollutants it contains.
If your vehicle does not pass inspection, there are a number of things that may be wrong, including a malfunctioning oxygen sensor, catalytic converter, exhaust gas recirculation valves, or evaporative controls. If your vehicle does not pass inspection or you want to prepare your car for inspection with an annual tune-up, we are here to help you.