We offer valleywide mobile windshield replacement services. 

What Goes Into Emissions Testing? It’s Not Just About Smoke

Fear not, fellow driver! This article will break down the process of emissions testing in a way that’s easy to understand. We’ll cover what gets tested, why it’s important, and how to prepare your car for a smooth test. While Premiere Auto Glass specializes in keeping your car’s windows clear and safe, overall car health is important. A critical part of maintaining a healthy vehicle is ensuring it passes emissions tests. These tests measure how much pollution your vehicle releases and help keep our air clean. But what exactly goes into an emissions test?

Why Do We Have Emissions Testing?

Imagine a city street filled with cars spewing out thick, black smoke. That’s what things were like before emissions standards! Nowadays, thanks to regulations and testing, vehicles produce significantly less pollution.

Here’s why emissions testing matters:

  • Cleaner Air: Ensuring cars meet emission standards reduces air pollution, leading to cleaner air for everyone. This helps improve public health, especially for those with respiratory problems.
  • Reduced Smog: Emissions testing helps control smog, that hazy layer of air pollution often seen in urban areas. Reduced smog improves visibility and overall air quality.
  • Greenhouse Gases: While not the sole focus of most emissions tests, some screen for greenhouse gases contributing to climate change.

What Gets Tested During an Emissions Test?

The specifics of an emissions test can vary depending on your location and the age of your car. However, some general components are always checked:

  • Hydrocarbons (HC): These unburned fuel molecules contribute to smog and other air quality issues.
  • Carbon Monoxide (CO): This colorless, odorless gas is produced by incomplete fuel combustion and can be harmful at high levels.
  • Nitrogen Oxides (NOx): These gases contribute to smog and acid rain.
  • On-Board Diagnostics (OBD): Modern vehicles have computer systems that monitor engine performance and emissions. During the test, a machine will check the OBD system for any emissions-related trouble codes.

How to Prepare Your Car for an Emissions Test

Here are some simple steps you can take to ensure your car sails through its emissions test:

  • Check Your Owner’s Manual: Your manual will likely have information specific to your car’s emissions system and any recommended maintenance before a test.
  • Schedule a Tune-Up: If your car is due for a tune-up, consider completing it before the test. A well-tuned engine is more likely to pass the emissions test.
  • Replace Old Spark Plugs: Worn-out spark plugs can affect combustion efficiency and lead to higher emissions. Consider replacing them if they’re nearing the end of their recommended lifespan.
  • Check Gas Cap: A loose or faulty gas cap can allow fuel vapors to escape, increasing emissions. Make sure your gas cap is on tight and secure.
  • Warm Up Your Engine: Most emissions tests are performed on engines that have reached operating temperature. Drive your car for a short while before heading to the testing center.

Remember: These are just general tips. It’s always best to consult your mechanic or local emissions testing center for specific advice related to your vehicle.

What Happens During the Emissions Test?

The actual emissions test is typically a quick and straightforward process:

  1. Arrival: You’ll pull your car into a designated bay at the testing center.
  2. Pre-Test Check: A technician may visually inspect your car’s exhaust system and ensure all necessary components are present.
  3. OBD Check: The technician will connect a machine to your car’s OBD port to read any trouble codes. 4. Emissions Test: The technician will connect a device to your car’s exhaust pipe and take a sample of the exhaust gases. The machine will analyze the sample to measure the HC, CO, and NOx levels.
  4. Results: Once the test is complete, you’ll receive a printout. If your car passes, you’ll be good to go! If it fails, the results typically indicate which specific emission is out of range.

What Happens If My Car Fails the Emissions Test?

Don’t panic! Failing an emissions test doesn’t necessarily mean your car is unsafe to drive. However, you’ll need to address the issue and get your vehicle retested before you can register it again.

Here’s what to do if you fail:

  • Consult a Mechanic: Take your car to a qualified mechanic and explain the emissions test results. They can diagnose the problem and recommend repairs to bring your vehicle within emission standards.
  • Get Repairs Done: Have the mechanic fix the identified issue(s) that caused the test failure. Common repairs might involve replacing faulty sensors, cleaning clogged parts, or repairing the exhaust system.
  • Retest: Once the repairs are complete, take your car back to a certified emissions testing center for a retest. Many facilities offer a free retest within a certain timeframe after the initial failure, so be sure to ask about their policy.

Additional Considerations

  • Cost: Emissions testing fees can vary depending on your location. The cost of repairs to address a failed test will also depend on the specific problem.
  • Exemptions: Some older vehicles or those with specific modifications may be exempt from emissions testing requirements. Check with your local Department of Motor Vehicles (DMV) for details.
  • Waivers: In some areas, hardship waivers may be available for individuals who cannot afford repairs to pass an emissions test. Contact your DMV to see if you qualify.

Statistics on Emissions Testing

The Environmental Protection Agency (EPA) estimates that emissions testing programs help reduce vehicle hydrocarbon emissions by up to 50% and carbon monoxide emissions by up to 70%. Source.


Emissions testing is vital in keeping our air clean and protecting public health. Understanding what goes into the process and taking steps to prepare your car can ensure a smooth testing experience. Remember, Premiere Auto Glass is here to help you with all your auto glass needs, and a healthy running vehicle is important for everyone on the road!

Emissions Testing FAQs

In addition to understanding the process of emissions testing, here are some frequently asked questions (FAQs) to solidify your knowledge:

How often do I need to get my car emissions tested?

Testing frequency varies by location and vehicle age. Check with your local Department of Motor Vehicles (DMV) for specific requirements in your area. It typically ranges from annually to biennially (every two years).

Where can I get my car emissions tested?

Authorized emissions testing centers are located throughout most areas. You can find a list of certified facilities on your DMV website or by searching online.

What happens if I don’t get my car emissions tested?

Driving an untested vehicle may result in fines or even prevent you from registering your car.

Can I modify my car to improve emissions?

Certain modifications, like installing a high-flow catalytic converter, can improve emissions output. However, such changes may not be legal in your area and could void your car’s warranty. Always consult your mechanic and check local regulations before making any modifications.

What are the health benefits of emissions testing?

Emissions testing helps improve public health by reducing air pollution, especially for those with respiratory problems like asthma. It can also relieve symptoms like coughing, wheezing, and difficulty breathing.

Follow Us