The Smog Check: What Is It? How Does It Work?

As a driver, you have a responsibility to keep your vehicle in good repair. This is regulated in a number of different ways, and in many states, passing a smog check is an integral part of proving that your car is suitable for driving.

The Purpose And History Of Smog Checks

Mechanic holding clipboard and doing a smog check on a car

As you might have already gathered from the name, smog checks are intended to ascertain whether or not your vehicle is emitting unsuitable levels of exhaust pollutants. In the United States, smog checks are most commonly associated with California, where they’ve been mandatory for most vehicles for decades. However, there are 32 other states that have some form of regulated emission check process in addition to California.

Irritatingly, smog check standards and procedures vary from state to state. The California requirements are notorious for being unique and exclusive; the state does not recognize emission checks performed in any other state, regardless of how closely the requirements match California’s. This makes it important for you to check emissions regulations whenever you relocate your vehicle to a new state, no matter how recently it has passed an emissions check.

Auto Systems Inspected During A Smog Check

Obviously, your car’s exhaust is going to be carefully tested during a smog check. Most shops, like All Makes Auto Repair Tucson, may just list the service under “vehicle inspections.” This is far from the only check performed during most emissions checks, though; the process can get extremely thorough and take thirty minutes or more to complete. Common additional procedures included in a smog check are a dynamometer test to measure powertrain efficiency and an electronics check to test onboard computer systems that can affect emissions quality.

Although recording requirements vary from state to state, in many areas the results of official smog checks are registered automatically and electronically with the local DMV. This makes it difficult or impossible to avoid the consequences of a failed smog check; these include (potentially quite expensive) repairs and forfeited inspection fees. In many states, private companies offer their own smog checks so that drivers can find out in advance whether or not their vehicles will pass the official state inspection.