--- title: "California’s ECU Tuning Policy: Your Questions Answered" description: "The Drive's editors look to clarify California's ECU tuning policy update so you pass your next scheduled emissions test." date: "2021-07-19" modified: "2021-07-19" authors: - name: "Jonathon Klein" job_title: "Contributor" link: "https://www.thedrive.com/authors/jonathon-klein" url: "https://www.thedrive.com/cars-101/41603/california-ecu-tune-flash-faq" categories: - "Culture" - "News" tags: - "commerce" --- # California’s ECU Tuning Policy: Your Questions Answered ![]() *\www.thedrive.com\* Last week, the folks at our sister site *Car Bibles* reported that the [California Air Resource Board]() was readying new enforcement on emissions diagnostic testing designed to sniff out vehicles with unapproved engine tunes and fail them during an emissions test. And indeed, after a quick scroll on the governmental agency's website responsible for California's vehicle emissions policy, they're out to squash unapproved tunes. Given we're all enthusiasts who've modified a car (or seven) in our time, as well as seekers of the truth, *The Drive's* Guides & Gear editors wanted to know more. And like us, we knew that you'd have questions worthy of further enlightenment. To that end, we reached out to CARB—which sets California policy—as well as the [California Bureau of Automotive Repair]()—the party responsible for the physical testing of your vehicle—to illuminate those still-darkened areas of how this policy came into effect, how it affects you, which cars are subject to such tests, and more. ![2020 Toyota Supra 3.0]() *Das Supra. , *Jonathon Klein** Before we get into those questions, though, let's talk about the policy and what it actually states. Going into effect on July 19, 2021, the new enforcement—which CARB told *The Drive* in an email is actually old policy but one that hasn't been fully enforced until now—is meant to catch emissions defeating engine tunes or ECU maps by aftermarket tuners. The enforcement is part of California's Vehicle Code and is based especially on [Section 27156, parts (C) and (D)](). That specific portion of the law states: > "(c) No person shall install, sell, offer for sale, or advertise any device, apparatus, or mechanism intended for use with, or as a part of, a required motor vehicle pollution control device or system that alters or modifies the original design or performance of the motor vehicle pollution control device or system. > (d) If the court finds that a person has willfully violated this section, the court shall impose the maximum fine that may be imposed in the case, and no part of the fine may be suspended." > — California Vehicle Code, Section 27156, part (c) and (d) Based on this, CARB and CBAR can access your car's ECU through its OBDII port during an emissions test and see if there are any unapproved vehicle tunes. A statement provided to *The Drive* via email by a CARB official goes into the reasoning behind the new push for enforcement. "We have had enforcement cases against manufacturers and distributors of aftermarket parts based on this issue. And the best examples of all are the alterations of vehicles such as VW did. So it's always been illegal and vehicles failed when discovered. It's just been something that typically was only found if the vehicle failed an OBD check or the smog technician noticed physical tampering with the computer or an add-on box. Or in some extreme cases, a police officer cited a grossly smoking vehicle, for example, a diesel truck 'Rolling Coal'." The official added, "Since the beginning of computer-controlled vehicles, software has always been an important part of the emissions control system. So we have always been very clear with the industry as to their responsibility to obtain an EO ([Executive Order]()) to ensure their modifications are legal for their customers. Once OEMs broke our trust with their software cheating, there was ample notice that we would be using all tools available to ensure everybody was following the rules, including the aftermarket." We also reached out to CBAR to clarify further questions but haven't heard back at the time of writing. We'll update this and other stories if we hear back from the agency that changes the reasoning behind the enforcement update. For now, though, let's get into a few other FAQs you may have about your tuned car and whether or not you're about to fail your next emissions test. ![2021 Ford Mustang Mach 1]() *Mustangs are tuner cars too. , *Ford** ## FAQs on California's ECU Tune Policy You've got questions. *The Drive* has answers! ## Let’s Talk: Comment Below and Reach Out to the Guides & Gear Editors We’re here to be expert guides in everything “how to” related. Use us, compliment us, yell at us. Comment below, and let’s talk. You can also shout at us on Twitter or Instagram or reach us all here: guidesandgear@thedrive.com. - Jonathon Klein: [Twitter]() | [Instagram]() - Tony Markovich: [Twitter]() | [Instagram]() - Chris Teague: [Twitter]() | [Instagram]() - Hank O'Hop: [Twitter]() | [Instagram]() ## Author Jonathon is the former Managing Editor for Commerce at The Drive and has been writing about cars and motorcycles for over a decade, but he's been known to scribble pretty things about adoption, tattoos, life, gear, adventures, food, technology, nature, and more. ### Author social links [Instagram]()