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  • Smog Pros Milpitas

5 Tips to Consider Before Getting a Smog Test

Updated: Feb 13, 2021

During the 1960's, smog levels in California were at it's most dangerous with more and more vehicle's on the road and no laws in place to curb emissions. That changed in 1970, with the passing of the Clean Air Act and the development of the California Smog Check Program. Californians saw a major decrease in smog levels which improved the health and safety of its residents.

A smog test or smog certification is required in the state of California in order to maintain the air stays fresh and clean. Whether you are renewing your vehicle's registration, changing ownership, or in the process of registering an out of state vehicle, a smog test may be daunting task for some. Here are 8 Tips to consider before getting a smog test.

  1. Check Engine Light - If you take your vehicle to a smog test station with the check engine light on, it's an automatic test failure. It is best to have your vehicle diagnosed by a certified auto technician to find out the cause of the check engine light and to repair your vehicle if necessary.

  2. Maintain Your Vehicle - Maintaining your vehicle with scheduled oil & filter changes, following recommended 30K, 60k, and 100K service intervals will keep your vehicle running smoothly and at it's optimal performance in order to help keep emissions down.

  3. Inflate Tires - Making sure your vehicle's tire pressure is even and correct allows for better stability and accuracy during the smog test. This is especially pertinent for vehicles that are 1999 and older, which will be driven on a dynamometer while a sample of its exhaust is collected by the smog test machine. Vehicle's with greater stability show improved overall emissions output by allowing the engine to maintain a constant and steady load. More importantly, maintaining your tire pressure keeps you safer on the road.

  4. Battery Recently Replaced or Disconnected - If you replaced your vehicle's battery or it was jump started or disconnected recently, it is best to hold off on a smog test. Whenever a vehicle's computer (engine control unit) loses power, its internal self test monitors are erased. Without the data from these required emissions monitors, your vehicle will most likely not pass. You will be required to drive between 100-200 miles over the course of a week called a "Drive Cycle," in order to complete the emissions monitors which allow your vehicle to pass a smog test.

  5. Vehicle Required To Get A STAR Certified Smog Test - At the top of your vehicle's registration notice, some may be required to take their vehicle to a STAR Certified smog test station or a regular Smog Test station. STAR stations are more closely monitored by the Bureau of Automotive Repair, and are required to go through an extra layer of certification and perform more involved testing. California state law mandates that a certain number of vehicles per referred to STAR smog stations. Not all smog test stations are STAR Certified so make sure you know which type of smog test is required for your vehicle.

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Joseph Heller
Joseph Heller

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