Why People Are Suddenly Freaking Out Over California's Exhaust Laws: Explained

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On Jan. 1, 2019, a new rule went into effect changing the way California cops can bust you for exhaust noise violations and the car community seems to be freaking out about it. The legislation in question is California Assembly Bill 1824, here’s a rundown of what it really means.

The short story is that A.B. 1824 is not as big a deal as some forum posters and YouTube clips have made it out to be, largely because California’s exhaust laws have been strict for a long time. Even as a Californian myself, I didn’t realize how many people wanted to discuss this until I saw a popular thread on Reddit’s r/cars and a cascade of videos on YouTube about it.


That said, it did become easier to get fined for being loud this year.

The Specialty Equipment Market Association (SEMA) spells the situation out pretty plainly in a press release:

California Assembly Bill (A.B.) 1824, which was signed into law by then-Governor Jerry Brown in June of 2018 went into effect on January 1, 2019. The bill has generated significant concern amongst the online enthusiast community. Despite what is being circulated, enactment of A.B. 1824 does not change existing laws pertaining to exhaust noise or sale and installation of aftermarket exhaust systems.

Under existing law, exhaust systems installed on motor vehicles with a manufacturer’s gross vehicle weight rating of less than 6,000 pounds, other than motorcycles, may not exceed a sound level of 95-decibels when tested under Society of Automotive Engineers (SAE) test procedure J1169 (May 1998). This was not changed by A.B. 1824.

A.B. 1824 amended how excess exhaust noise violations are handled by law enforcement. Beginning this year, a vehicle cited for violating the current exhaust noise law will no longer receive what is known as a “fix-it” ticket. Instead, violations will result in an immediate fine.


In fact, aftermarket trade group SEMA has a pretty comprehensive guide to the situation for your reference. We’ll break it down a little further so everybody can get on the same page, and hopefully we can all avoid getting fined.

What does the rule say exactly?


California Assembly Bill 1824, as it was approved by the governor on June 27, discusses rules around voting, compensating victims for crimes, operating veterans’ housing, and as relevant to us: escalating the punishment for having an exhaust that the police decide is too loud.

Assembly Bill No. 1824, Chapter 38, (4):

Existing law provides that whenever any person is arrested for certain offenses, including, among other things, an infraction involving vehicle equipment, the arresting officer is required to permit the arrested person to execute a notice, prepared by the officer in triplicate, containing a promise to correct the violation and to deliver proof of correction to the issuing agency, unless the arresting officer finds that a disqualifying condition exists.

Existing law requires every motor vehicle subject to registration to be equipped with an adequate muffler in constant operation and properly maintained to prevent any excessive or unusual noise and prohibits a muffler or exhaust system from being equipped with a cutout, bypass, or similar device. Existing law further prohibits the modification of an exhaust system of a motor vehicle in a manner that will amplify or increase the noise emitted by the motor of the vehicle so that the vehicle exceeds existing noise limits.

This bill would include, among those conditions that are disqualifying, a violation of the above-described requirements related to mufflers and exhaust systems.


What does that mean in plain English?

Before 2019, California cops could pull you over for having a loud exhaust but they would issue a “fix-it ticket.” That means that if you went back to them with a stock exhaust reinstalled within a certain amount of time, you would be free and clear.


Police are not allowed to do that anymore, and now will just give you a violation on the spot.

How do cops decide if my exhaust is illegal?


There are two things the state of California cares about when it comes to your car’s exhaust: How loud it is and how much it pollutes. Biannual smog testing means your car has to pass an emission test to stay street legal, but noise enforcement is a little more vague.

Per California Highway Patrol Bulletin NO.98-100: “Excessive Noise is primarily a nuisance issue rather than a safety concern, and determination of excessive noise is subjective. For this reason, enforcement personnel are to exercise sound professional judgment in making a determination of violation.”


Rules on the books governing mod’d exhausts would be Division 12 of the California Vehicle Code, sections 27150-27159, which basically just says “you need some kind of muffler”, and sections 27200-27207 which states that your vehicle should be below the noise limit “at a distance of 50 feet from the centerline of travel.”

That limit, by the way, is 95 dB as outlined in subheading (b) of Article 2, section 27151 of the aforementioned Vehicle Code.


So how exactly do they measure 95 dB?

Like I said, practically speaking it’s going to come down to the cop.

If they think you sound too loud, they can pull you over and slap you with a ticket. So those of you with wide pipes might be wise to coast with your clutch in when you pass a parked police car.


But technically speaking, the California Vehicle Code says SAE J1169 is the measurement standard. That means the exhaust noise should be measured at a constant RPM, though frustratingly I’m having a really hard time finding the exact testing methodology.

I did reach out to the Society of Automotive Engineers and will update this post if they get back to me. In the meantime, this video appears to show what the test might look like: microphone is held half a meter away from the exhaust port at a 45-degree angle.


How loud is 95 dB really?


So 95 dB is pretty darn loud. OSHA requires hearing protection for workers who are subjected to an average of 85 db over an eight-hour shift. A jet airplane taking off 82 feet away is supposed to be 150 dB; loud enough to rupture your eardrum. Purdue University has a nice chart if you want some more examples.

For some automotive reference–according to the United Kingdom’s Vehicle Certification Agency, a Jaguar F-Type SVR receives a noise rating of 74 dB. And that has the loudest factory exhaust, I think, I’ve ever heard. Granted, the Brits might measure vehicle sound slightly differently than American police, but you get the point: a 95 dB exhaust would be hard to ignore.


I once measured 108 dB myself with an F-Type SVR, hard launching through LA’s second street tunnel with the windows down and a microphone in my pocket. (The things I do for you people, and for science!) The auditory experience in real life was genuinely jarring.

I have a modified exhaust in California, what do I do?

All aftermarket exhausts are not automatically illegal in California.

If your car is registered in California and you want to put an aftermarket exhaust on it, or it already has one, you’re going to want to make sure it has an Executive Order (EO) number.


That’s basically a stamp of approval from the California Air Resources Board (CARB) which means the part is CA legal. Smog Tips has some more details about this, and CARB even has a website for looking up parts to see what’s legit before you go shopping.

That EO number should be your ticket to passing your biannual smog check and avoid getting a ticket from a cop if you get pullover.


I already got a ticket for this, what do I do?


If you got popped and cited for making too much noise, you will have to go to an official Referee Center. Unless you can talk your way out of a ticket on the side of the road, but I wouldn’t know anything about that.

According to the Bureau of Automotive Repair, basically what happens next is you have to bring your car into compliance and then bring it into a Center. Don’t sleep on this–your citation might have a court date, and you’re going to want to sort this out before that comes.


If your car is quieter than 95 dB, and all your emissions-related parts have an EO number, you should be good to go even if the cop wanted to find you.

When you do satisfy the Referee Center’s requirements one way or another, the nice people there will issue you a “Certificate of Compliance” which you can take to court to prove that you’ve gone legit.


I might also recommend listening to automotive lawyer Steve Lehto’s podcast about what you should check before paying an exhaust fine.

How much is the fine?


According to the 2019 edition of the Uniform Bail and Penalties Schedule, it can be quite a bit. The “base fines” don’t look too bad but if you start reading right the numbers get scary, including a $1,105 fee total for certain “Motor Vehicle Exhaust Standards” violations, and the same if you have a whistle-tip. That’s stiff.

(Also, I can’t believe whistle-tips got their own shoutout on the penalty schedule, and are somehow a thing even now. Please tell me you remember Bubb Rubb? Obviously, the grumpy old people in that famous KRON4 video got their way.)


Can you list out all the important California exhaust rules one more time?

These links will help you get educated on the laws regarding aftermarket exhausts in the state of California:




All aftermarket exhausts did not become illegal in California on Jan. 1, 2019. Every exhaust system that was legal last year is still legal this year.

It did just become a lot easier for California cops to hit you with a fine if you are breaking the existing rules, though. And while there are specific rules on what constitutes “too loud,” it’s going to come down to a police officer’s discretion in the field.


See the links above to figure out if your car is in compliance with the law, and what to do if you get ticketed for excessive noise now.

I have tried to be as comprehensive as possible here, but if you have an anecdote or additional piece of information on this I’d encourage you to leave a comment.