Back to all

Passing the Test (How to Prevent Emissions Test Failure)

January 1, 2021

Vehicle emission testing has become ubiquitous in North America and for a good reason.  Clean air quality is important for the environment and all of us.  Since vehicle emissions are among the main causes of air pollution, emission testing can alert you to problems in your vehicle than can be fixed so it won't needlessly pollute.

Emissions tests are looking for certain toxic gases internal combustion engines produce, such as nitrogen oxide, particulate matter, non-methane organic gases and formaldehyde.  Emissions control systems reduce these gases if they are working properly. 

The best way to minimize pollution is to keep those vehicle systems working properly, and periodic inspection and maintenance is the key.  So if you want to make sure your vehicle will pass an emissions test, it helps to know what might go wrong.

Let's start on the easy one.  Your gas cap could be loose, allowing vapors to escape into the atmosphere.  The most common solution is to replace it.  Or your air filter may be dirty.  A dirty air filter may push your hydrocarbons pass the acceptable level.

Now to the more complicated things.  The mixture of fuel and air in your engine may be tilted toward the "too much fuel" side.  That could cause problems for your vehicle's catalytic converter, a device that converts toxic gases from your exhaust into less toxic pollutants.

Your vehicle has a closed system that prevents fuel tank vapors from escaping into the air; it's called the EVAP system.  A technician can track down problems.

Vehicle engineers have gone to great lengths to minimize the amount of pollution your vehicle produces.  Your vehicle's manufacturer recommends how frequently those systems need servicing.  Keep those systems in good shape and you're likely to pass emissions tests with flying colors.  Neglect them and you might find your vehicle failing an emissions test.  When that happens, you'll have to get the problems repaired before you can get back on the road.

Tuffy Lake In The Hills
59 West Acorn Lane
Lake In The Hills, Illinois 60156
847-854-9850

More articles from Tuffy Lake in the Hills

Why is My Brake Pedal Hard to Push?

March 15, 2026

When you push on your brake pedal, you should find your vehicle easy to stop. But at some point, you might notice stopping takes much more pressure on the pedal than it used to. When it gets to that point it becomes a safety issue, and you should bring your vehicle in so we can track down whats... More

The Engine Gets a Boost (Turbocharged Engine Maintenance)

March 8, 2026

If someone told you that your vehicle could have the same power but with a smaller engine, wouldn't that sound like great idea? Just think, a smaller engine would save you money at the gas station and you'd still get the same horsepower. The technology to do just that has been around for a long t... More

Feeling Powerless (Why Is My Battery Light On?)

March 1, 2026

When one of your vehicles warning lights comes on, the first thing that comes to mind is, Oh, no, whats wrong now? When its the battery light, it means theres something wrong with your vehicles battery or charging system. And because both are important for your vehicle to work properly, its a go... More