Smog Checks: What Are They And How Do I Pass a Smog Test?

What Is a Smog Check?

Emissions test laws vary from state to state.
An emissions test is a regular vehicle test designed to determine how much potentially hazardous material is being emitted by your vehicle annually.
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Simply put, a smog check (also known as a smog test or emissions test) is a regular vehicle test designed to determine how much potentially hazardous material is being emitted by your vehicle annually. In general, these tests are designed to identify and remove vehicles that severely pollute from the roadways. If you’ve ever driven behind a car or truck billowing black smoke out of its tailpipe, then you can clearly see why this type of emissions test is necessary.

How Long Does One Take?

In general, smog checks take very little time at all, especially if you keep up with regular vehicle maintenance. Today’s mechanics are able to evaluate your vehicle’s emissions using the on-board diagnostics system (or OBD-II). By plugging into this system using a specialized meter, a mechanic will be able to certify your smog test in a fairly short time period.

Why Does My Vehicle Need To Pass a Smog Check?

Smog checks may be required by law in your state or jurisdiction. If so, you may need to take your vehicle to an auto mechanic on a regular basis to have it recertified. Otherwise, you may be fined, or your vehicle may have its license suspended. This is especially the case if the mechanic finds that your vehicle is polluting in excessive of predetermined standards.

Smog checks are also a great opportunity to check that all on-board components that track and manage harmful emissions are working as intended. Emissions canisters and the catalytic converter are known to degrade with time, which may increase your emissions. If you fail a smog check, you may be required to get these parts fixed before you are allowed to operate the vehicle legally.

How Do I Pass a Smog Check?

Preventative maintenance is perhaps the best method for ensuring that you pass a smog test.
Problems that cause issues on the smog check relate to the exhaust system.
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Preventative maintenance is perhaps the best method for ensuring that you pass a smog test. If you believe something is amiss – such as dark smoke emitting from your tailpipe – you should immediately consult with a mechanic. Often, problems that cause issues on the smog check relate to the exhaust system. Proactive checks on this system will certainly improve your chances of passing this important test.

Also, several seemingly-unrelated car components may cause troubles on a smog test. In order to pass a smog check, be sure that you have recently had your oil changed. Dirty oil produces more hydrocarbons, which may trigger a smog test against your favor.

In addition, be sure that your battery is providing ample energy at the time of your test. If it is not, replace the battery and postpone your test for two or so weeks. Because the on-board computer resets when the battery is replaced, you will need to drive for a little while before it stores enough information needed to pass a smog test.

If you pass your smog check, you’ll likely receive a certification sticker for your vehicle. Without this sticker, police officers may issue you a ticket for failing to meet compliance standards for emissions testing.

What Happens If Fail a Smog Check?

Depending on your state and jurisdiction, failing a smog test may prevent you from licensing your vehicle, making it illegal to operate. If this happens, the mechanic who performed your test will provide you with a list of repairs necessary to bring your car back up to standards.

Some jurisdictions provide discounts to help mitigate the cost associated with replacing non-compliant car parts. In some cases, such as in California, the state may even provide a voucher to retire an older vehicle.

Factors That May Affect Your Smog Check

There are also a wide variety of specialized car parts that may affect your smog test if they are faulty or otherwise ineffective.
One component that plays a key role in a smog check is the catalytic converter.
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Car age has been proven to be among the most reliable causes of smog test failures. Prior to 1990, when the federal Environmental Protection Agency instituted new regulations regarding smog emissions testing, vehicle manufacturers followed much weaker emissions standards. As a result, they are far more prone to emit harmful material in access of state and federal standards. Likely, the only resolution for this problem is to consider investing in a newer vehicle that was designed with modern emissions standards in mind.

There are also a wide variety of specialized car parts that may affect your smog test if they are faulty or otherwise ineffective. For instance, if the O2 sensor is damaged or is faulty, your vehicle’s on-board diagnostic system will be unable to determine if the catalytic converter is functioning correctly. If left unchecked, this may cause problems when a smog check is initiated.

Another key component that plays a key role in a smog check is the catalytic converter proper. Starting in 1975, all US vehicles have used one of these devices to mitigate the harmful emissions that result from burning petroleum as fuel. If your catalytic converter is faulty or is failing to reach the 800° F threshold needed to initiate the conversion, you will almost certainly find yourself on the negative end of an emissions test.

How To monitor Emission Levels Using an OBD-II Scanner

You can check your emissions levels at home, using an OBD-II scanner (available at most auto parts stores). After plugging this device into the appropriate OBD-II port on your vehicle and following the instructions, you’ll receive a variety of information regarding your car’s regular operating status. This includes information on your vehicle’s emission levels.

Proper emissions levels vary from state to state. As such, it’s in your best interest to take note of the emissions information output by the OBD-II scanner and bring it with you when you go to consult with a mechanic.

Conclusion

Knowing the details of a smog test can help you keep up with your vehicle’s maintenance and remain in compliance with local and state regulations governing harmful emissions. Smog tests are not exceptionally cumbersome, but they play an important role in keeping the air as clean and breathable as possible.

There are many actions you can take if you are seeking to pass an upcoming smog test. You can even check your emissions levels at home using an OBD-II scanner. If you believe there is something amiss with your exhaust system, don’t wait until a serious problem arises. Take your vehicle into a mechanic as soon as possible so that they can evaluate whether or not your vehicle’s parts are causing problems that would cause you to fail a smog test.

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