Smog checks are required for all auto owners in many states across the United States, especially in areas with high levels of air pollution. Throughout this process, the mechanics measure your car’s emissions to ensure it complies with the governmental regulations. That helps reduce the environmental impact of harmful gasses released from cars and trucks. Smog checks are a legal requirement for any car owner. They have been incorporated into the road regulations as a way to combat at least a part of air pollution and climate change.
What Is a Smog Check?
This is a test conducted on vehicles to measure the amount of pollutants they release into the air. Usually specific exhaust emissions are tested, such as hydrocarbons (HC), nitrogen oxides (NOx), and carbon monoxide (CO), which contribute the most to air pollution.
Why Are Those Tests Necessary?
Air pollution is increased through the exhaust pollutants from internal combustion engines. If the vehicle is poorly maintained or there is some issue with it, those pollutants are released in much bigger proportions. Then this contributes to smog, acid rain, and climate change. Smog checks make sure your car doesn’t release too many of those harmful gasses and small particles.
Air pollution also leads to major health damage to the population. It may cause respiratory problems, cardiovascular diseases, and other health issues. This is where those tests come in handy because they ensure that vehicles meet the proper standards and release less harmful gasses in the atmosphere.
In many states, including California, you’d need to pass such an inspection to renew the registration of your automobile. If you haven’t performed it or the car has failed, you won’t be able to legally drive your car.
How Often Do You Need to Test Your Auto?
The frequency of those tests depends on your location and the type of vehicle you drive. In California, for example, most vehicles are required to undergo one every year or twice a year. Yet, this may vary, depending on:
- Model and year of production
- The type of engine – gasoline or diesel engine
- The area of registration
Newer models (typically less than 8 years old) may be exempt from an inspection, but older cars undergo more frequent tests.
How Is the Test Performed
There are several steps:
Visual Inspection
A visual check of the emission control systems. Then they can see any issues with the components and their installations.
Functionality Check
The technician makes sure the emission control systems function well by scanning the on-board diagnostic (OBD-II) system. This system stores any error codes and by retrieving the information the technicians can see if there had been any malfunctions in the engine components.
Tailpipe Emission Check
Now comes the time for the tailpipe emissions test. A probe is placed in the tailpipe and you or the technician will need to run the vehicle at both idle and higher speeds to measure how many pollutants the car releases. Then the ‘pass’ or ‘fail’ score is determined by how well your vehicle complies with the state emission standards.
Types of Tests
Depending on the state and the type of vehicle, there are several types of smog checks.
Two-Speed Idle (TSI)
The vehicle is tested at both idle and at a speed of about 2500 RPM. The emissions should be under the state maximum limit at both speeds.
Acceleration Simulation Mode (ASM)
Here the technicians use a dynamometer to stimulate actual driving conditions. Then they run the vehicle at various speeds and measure emissions as close to real conditions as possible.
On-Board Diagnostics (OBD-II)
This part of the process checks to see for any emission-related faults. Such error codes can be stored in an OBD-II system that is integrated in most card manufactured after 1996.
For Diesel Cars
Diesel vehicles require a different type of testing. What’s measured here is the visible smoke from the tailpipe, along an inspection of the OBD-II system.
Smog Check Near Me: Finding a Certified Station
It’s not hard to find the closest or best test station near you. There are many online directories or you can browse the website of the Department of Motor Vehicles (DMV). The search can be narrowed down by ZIP code or city and this makes it even more easy to find a station near you.
Or you can use search engines. For instance, if you live in Sacramento, type “smog check Sacramento” in the search bar to find nearby certified testing centers.
What are the Prices
Prices typically vary. They are different by location and even by type of vehicle. In California, for instance, you’ll find a range from $30 to $60. Yet, it’s not a one-case-fits-all scenario so you may need to pay a lower or a higher price. Mostly depending on the testing center and the required processes (e.g., diesel vehicles may come with bigger expenses).
Common Reasons for Failing an Emission Test
Usually failing the check is due to simple-to-fix issues that the mechanics can easily diagnose and repair. Some of those are:
Check Engine Light On
If the check engine light is on, you’ll fail the test. Usually the oxygen sensor is the culprit behind this issue. If it malfunctions, it can’t check properly how much unburned oxygen there is in the exhaust and this leads to incorrect air-fuel mixture. Then, of course, the fuel doesn’t burn as efficiently and the emissions are higher. Still, it’s a simple fix for most auto repair shops.
Worn Out Catalytic Converter
A damaged or worn out catalytic converter cannot properly turn the pollutants into less harmful gasses before they leave the exhaust system. Then, naturally, emissions are higher. Yes, this is a much more expensive car issue to solve but one that must be done if you want to pass the smog check and drive your car. Yet, if the catalytic converter isn’t that damaged but you haven’t driven your car often, make sure to drive on the highway for some time around two weeks before the test. Then the oil and gas residues can be properly removed and you’ll have a bigger chance to pass the smog check. If you drive rarely and at lower speeds, the catalytic converter doesn’t reach high enough temperatures to do its job properly.
Dirty oil
If the oil has gotten dirty, you’ll not be able to pass the smog test. So, make sure you’ve done an oil change recently.
Dirty Air or Fuel Filter
Dirty air filter restricts proper airflow to the engine. Usually you can simply replace it and that’s a step you should go through at least once a year. On the other hand, if the fuel filter is dirty, it cannot properly filter and clean the fuel, leaving more emissions.
Problems with the EGR Valve
The Exhaust Gas Recirculation (EGR) valve recirculates a portion of the exhaust gasses back into the combustion chamber. Clogged or malfunctioning valve increases emissions and you’d need to clean or replace the problematic part.
Excessive Carbon Buildup
Carbon build-up inside the engine and exhaust system increases emissions. But you can take steps to prevent that from happening. Usually, by putting a fuel additive into the fuel tank so that it can clean the excess carbon and lower down emissions. Or you can leave your car to the professionals with a carbon cleaning service at a repair shop.
Improper Tire Pressure
Smog checks with a dynamometer test will be influenced if the tire pressure is not balanced or up to the standards of the auto or tire manufacturer. So, inflate the tires properly and you’ll be able to avoid this issue.
What Happens if You Fail a Smog Check?
If your car fails, the technician will tell you what the issues are and you’d be able to repair them and retest. If you don’t have enough finances, some states offer financial assistance to help cover the cost. Remember, you need to make sure the car’s emission system functions properly if you want to renew your registration.
This is an essential process for all car owners. Without passing the emission test, you cannot renew the registration of your vehicle which will leave you unable to drive it. Making sure your car is in top condition and doing all the needed repairs will allow you to pass the test and continue driving.