California Vehicle Inspection Requirements

October 2nd, 2017 by

California Smog

Each state has their own vehicle inspection requirements, and California is notoriously strict. In order to renew your vehicle registration, your car must pass a biennial smog check, which has varying program requirements depending on your zip code. A smog check is mandatory for all out-of-state vehicles, whether your previous state required emissions inspections or not. Out-of-state vehicles also must undergo a VIN inspection upon registration.

Emissions Testing FAQs

What Happens If My Car Fails An Emissions Test?

The bottom line is if you don’t pass a smog check, you can’t register your vehicle until you qualify once more. That means no license plates and no legal standing to drive. Receiving a failing grade from an emissions check center is stressful for sure, but it should also come with a slip or report from the attendant detailing exactly what needs to be fixed. Bring your slip to a trustworthy service center like Mercedes-Benz of Sacramento, and we’ll get to work on repairing your car. Once we’ve made the necessary repairs, you are good to return to the emissions check center for a re-test and to earn your smog test certificate. We recommend scheduling repairs as soon as possible before your registration date arrives, so your plates don’t expire while your car is in our shop.

What is Done During an Emissions Test?

During a emissions test or smog check, your vehicle is measured for the levels of hydrocarbon (HC), carbon monoxide (CO), and nitrogen oxides (NOx) that it emits. Depending on your vehicle, these test are administered:

  • Gas Cap Pressure Check: All vehicles are tested to see if the gas cap is effective at keeping vapors from escaping. An effective gas cap prevents fuel waste and can improve gas mileage, while also preventing smog.
  • On-Board Diagnostics (OBD II) Test: Vehicles that are model year 1996 or newer are tested by using your vehicle’s on-board computer data to check for malfunctions.
  • Inspection and Maintenance (I/M 93) Test: Vehicles that are model year 1981 through 1995 have their vehicle emissions control equipment tested by analyzing tailpipe emissions. Driving is simulated by placing your vehicle on a dynamometer, or a treadmill device, and emissions are captured and analyzed. Your vehicle needs a functioning exhaust system and brakes, and to be free of major fluid leaks in order for this test to be administered.
  • Single Idle Speed (BAR 90) Test: Vehicles that are model year 1976 to 1980 are analyzed to see if their emission control equipment is working properly. A sensor is placed on the hood to measure engine speed, while a metal probe gathers a sample of the exhaust stream from the tailpipe. Your exhaust system must be intact and leak free to qualify for this test. 

How Do You Pass An Emissions Test?

You’ll pass an emissions test so long as your car is well-maintained, functions at peak performance, and you take care of service issues right away. Here are some tips for passing an emissions test:

  • Don’t wait to get maintenance and repairs. Issues with your vehicle will worsen and important parts and systems will fail.
  • Don’t get an emissions test if you suspect service issues or malfunctions
  • Trouble codes from your Check Engine Light indicate that your vehicle needs immediate attention. Don’t ignore these signals.
  • If your vehicle is up for the dynometer test, check tire pressure and condition, and inflate them if necessary.
  • Check engine oil and vehicle fluids.
  • Drive your car for 20 minutes prior to a smog check to ensure your vehicle is running optimally.
  • Always rely on profession, highly trained technicians.


Is Anyone Exempt from California Smog Checks?

Eco-conscious drivers get a bit of a break when it comes to emissions tests and mandatory inspections. The state of California does not require biennial testing for:

  • Hybrids
  • Electric vehicles
  • Motorcycles
  • Natural-gas-powered vehicles weighing more than 14,000 pounds
  • Diesel-powered vehicles made before 1997 OR have a gross weight over 14,000 pounds
  • Vehicles made in or prior to 1975
  • Newer vehicles that are less than six years old


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