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Make sure you know the exhaust law before you break it!

Quick notes

California has a noise pollution law that prohibits exhaust sound emissions.

This new California exhaust law means that more drivers are being ticketed.

California Noise Pollution Law

California Assembly Bill 1824 brought a new rule into effect on January 1, 2019. This rule outlines how California police enforce exhaust noise violations. It did not change the pre-existing laws relating to exhaust noise and aftermarket exhaust systems, just how they’re enforced.

The law is that vehicles with a manufacturer’s gross vehicle weight of fewer than 6,000 pounds cannot exceed 95 decibels when tested. This does not apply to motorcycles.

“California is known for being at the forefront of environmentalism and emissions. This includes sound emissions. “

The standard by which the sound level is determined is governed by the test procedure J1169 of the Society of Automotive Engineers.

If a vehicle is stopped by the police or other enforcement and the exhaust noise exceeds 95 decibels, the driver is immediately fined. Prior to California Assembly Bill 1824, if a driver was found to have an exhaust exceeding 95 decibels, they were provided with what is called a fix-it-ticket.

This gave them a certain amount of time to correct the issue, and upon proof of the new sound emission, the ticket was cleared. There was no immediate fine, like now.

How is it determined that exhaust is illegal?

According to the California Highway Patrol Bulletin No. 98-100, the concern with noisy exhausts is that it’s a public nuisance issue. They acknowledge that whether the noise is excessive is a subjective judgment, and law enforcement is to use their professional discretion in determining whether a violation has occurred.

“California is known for having greater-than-average auto customizations and many auto enthusiast clubs.”

How does one determine whether their customized exhaust system will meet the legal standard? Sections 27150-27159 of the California Vehicle Code Division 12 outlines what is required of the exhaust system. The sections indicate that there has to be a muffler on the vehicle.

Sections 27200-27207 outline the sound requirements, which is that the noise emitted should be below the limit from 50 feet from the centerline of travel. The limit of 95 decibels is outlined in section 27151 Article 2 (b) of the same code.

This California muffler law is enforced by the police, so in reality, it’s going to be the police who determine whether your exhaust sound emissions are over the limit. In that respect, the new California exhaust law has not changed anything.

What to do if you have a modified exhaust


Aftermarket exhausts are not automatically over the 95 decibel sound emissions limit. Because of the significant customizations market in the state, the California Air Resources Board allows aftermarket exhausts that pass the 95-decibel test to be branded with an Executive Order (EO) number.

This indicates it has their seal of approval. If pulled over by the police, this EO number should prevent you from being ticketed for a noisy exhaust.

You already have the ticket, what to do now?

Once you have the ticket, you will either want to have the exhaust tested to ensure it is under the 95 decibels limit, or you will need to make sure that your car complies with the law.

To do this, you would need to go to a Referee Center. Your car will be tested. If it passes, great. If not, you will need to make changes to be granted a compliance certificate.

“Make sure that your car is in compliance with the law.”

This certificate will also be granted if the noise decibels were tested as below 95. The certificate should then be submitted to the court. For specific information as to how the ticket and compliance should be dealt with, contact an appropriate legal professional.

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