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California is famous among consumers and enthusiasts alike for its strict emissions laws. Now, the California Air Resources Board (CARB) has introduced new regulations for modified cars. Apparently, the new law is supposed to check for an ECU tune while smog-checking it, determining whether or not you can register your car. Now, this all sounds rather complex, and it certainly has some serious ramifications for tuners and car enthusiasts.

What is a “tune”?

A NASCAR pit mechanic works on a laptop
All cars, even NASCARs run on some sort of tune | David J. Griffin via Getty Images

First, let’s get into what an ECU tune is. Basically, a tune tells your car to go faster by way of making your engine produce more horsepower. In reality, things are a little more complex. Deep within the bowels of nearly every car there lives a little computer, about the size of your hand, and twice as thick. That computer is called the “ECU”, or Engine Control Unit tells your car’s motor what to do and when.

A while back, people smarter than I figured out that you could get into that computer and tell it what to do, and by extension, your motor. Now, your car’s motor makes horsepower based on three parameters: air, fuel, and a spark from the spark plugs to burn it all. If you tell the computer to modify those three things to make more horsepower, well, you’ve got yourself an ECU tune.

CARB has to approve your tune to register your car

A mechanic uses a laptop to work on a Jaguar
Laptops are now a part of daily vehicle repair for mechanics | Marijan Murat via Getty Images

And that is exactly the issue that the California Air Resources Board has with ECU tuning. Any Joe or Jane Schmo with a laptop can do it. However, that same Joe or Jane Schmo can also do it improperly, and make the car’s emissions far worse. See: coal rolling. So, that’s what the new law aims to prevent; people from tuning their cars without thinking of the environment first.

Per CARB’s website, starting on July 19th, 2021, “vehicles with software not provided by the original equipment manufacturer… blah, blah …. or approved through a CARB Executive Order will fail smog check.” Bummer. Although, maybe not so much of a bummer if it helps to stop the widely disapproved act of rolling coal.

Emissions requirements will only get tighter

A man stares at an aftermarket exhaust system on display
An aftermarket exhaust can effect emissions | Alessandro Di Ciommo via Getty Images

That said, it was inevitable that something like this would happen. Frankly, it’s not a huge deal. Tuning companies will figure out how to make their tunes compliant, in the rare case they aren’t already, and life will go on. However, this is a sign of things to come. It likely won’t be long until we see a German TUV-style check on modifications here in the U.S, so enjoy that fire-spitting tune while you can.

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MotorBiscuit Writer - Sedans & Coupes

Chase Bierenkoven

Chase Bierenkoven has been obsessed with cars his whole life and now finds joy in sharing what he’s learned from his own daily drivers. Chase earned a Bachelor of Science in Criminal Justice and Criminology with a focus on legal studies from the Metropolitan State University of Denver and quickly became an automotive journalist. When he isn’t writing, Chase is either driving his passion project, a 2004 BMW M3 in Carbon Schwartz Metallic, or playing around Colorado’s terrain, mainly mountain biking and skiing.