Vehicle Exhaust Noise Level Certification

California law requires that all vehicles must be equipped with an adequate muffler to prevent excessive noise from the exhaust system. It also prohibits the operation of a passenger vehicle (other than a motorcycle), or a truck with a Gross Vehicle Weight Rating (GVWR) of less than 6,000 pounds, that has an exhaust noise level greater than 95 decibels, when tested under specified conditions.

If you have been issued a citation for operating a vehicle in violation of Vehicle Code Section 27150 or 27151, you must take your vehicle to a state Referee Center.

Note: The Referee is only authorized to inspect and certify passenger cars and trucks under 6,000 GVWR that have been cited for a violation of Section 27150 or 27151 of the Vehicle Code. The maximum decibel level applies only to those vehicles. Citations issued to other vehicles (motorcycles, trucks exceeding 5999 pounds GVWR) are not part of this program. Check with the agency that issued the citation, and/or the court, to find out how to show proof of correction for these other vehicles.

The following steps outline the procedures you'll need to follow to get a certificate of compliance, which shows your vehicle's exhaust noise level is within the applicable standards.

Step 1

If you feel your vehicle's exhaust system has been modified or has deteriorated so that the noise level exceeds current standards, you should have the exhaust system repaired before proceeding to step 2.


If you have reason to believe that your vehicle's exhaust noise level meets the current standards, proceed directly to step 2.

NOTE: Citations have a court appearance date. Timely action can help you avoid additional fines and penalties.

Step 2

Have your vehicle tested at a state Referee Center. To make an appointment, call the Referee Scheduling Center at (800) 622-7733. Have the citation and vehicle registration with you when you call. The Center will tell you any fees that will need to be paid for the test.

Step 3

The Referee will conduct an exhaust noise level test in accordance with Society of Automotive Engineers (SAE) standard J1492 (October 2008) to determine if your vehicle's exhaust noise level exceeds the noise standard (95db).

If your vehicle meets the standard, the Referee will give you a "Certificate of Compliance." Take the certificate to the court (See Step 5).

If your vehicle does not meet the standard, the Referee will give you a report that lists the recorded decibel readings. Your vehicle must be repaired to meet the standard of not more than 95 decibels (See Step 4).

Step 4

If your vehicle does not meet the standard, additional repairs must be made before you can make a second appointment with the Referee Scheduling Center.

Step 5

Once your vehicle receives a "Certificate of Compliance" from a Referee Center, present the certificate to the court as proof that your vehicle is in compliance with California law.

NOTE: Inspection fees and any necessary repairs are your responsibility. You may also be required to pay a fine and other legal costs when reporting to the court. Also, note that most citations have a deadline. Timely repairs can help you avoid additional fines and penalties.

If you have any questions, please contact the local law enforcement agency that issued the citation or the Bureau of Automotive Repair at (800) 952-5210.