California Smog Inspectors to Check for Illegally Tuned Vehicles

Beginning July 19, California’s Bureau of Automotive Repair (BAR) may fail motor vehicles during their “smog check” inspection if they are found to have software modifications (tunes) not provided by the original equipment manufacturer (OEM) or approved through a California Air Resources Board (CARB) Executive Order (EO). 

These changes have generated significant concern within the enthusiast community, along with some misinformation. Here are the facts.

What You Need to Know

  • In California, a vehicle’s software is considered part of its emissions system. Therefore, any modification to the vehicle’s software requires approval from the state through CARB’s EO process to be considered legal. This provision is not new. However, the state will now check to make sure your vehicle’s software is factory-stock or has received an approved EO from CARB. If not, your vehicle may fail its smog check. The SEMA Action Network (SAN) is working with BAR to ensure that vehicles modified legally do not inadvertently fail.
  • BAR anticipates approximately 5-10 vehicles will fail each day for illegally modified software. For context, BAR inspects approximately 1 million vehicles each month as part of the smog check program. Roughly 10,000 of these inspections result in failures due to problems other than modified software. In other words, BAR expects very few vehicles to fail for illegally modified software.
  • If your vehicle fails for illegally modified software, it must be restored to an OEM setup or CARB EO approved software configuration before it may be retested.
  • If your vehicle fails for illegally modified software and you believe it is already an OEM setup or CARB EO approved, you may schedule an appointment with the Referee for further inspection.
  • If you unknowingly purchased a vehicle with illegally modified software, you may file a complaint with BAR.
  • It’s important to note that BAR has had the authority to implement these changes since 2013 but has been gathering the data necessary to operate the program since at least 2015.
  • During a meeting of the BAR Advisory Group on July 15, BAR staff expressed confidence that non-tuning ECU modifications, such as aftermarket wheel and tire calibrations, would not result in failed inspections. A recording of the meeting will be posted to the California Department of Consumer Affair’s YouTube channel in the coming days.
  • To ensure equipment upgrades comply with emissions regulations, the SEMA Garage emissions compliance center helps manufacturers of performance related products, including ECU modifications, to obtain approved CARB EOs.

Questions? Please email