No California bill numbered AB 46 governs exhaust modifications or traffic stops. The rules drivers usually mean when they search for “California AB 46” and exhaust come from four Vehicle Code sections: Section 27150 and Section 27151 set the exhaust noise standards, Section 40303.5 makes most exhaust citations correctable as fix-it tickets, and Section 2806.5 (added by AB 2773 in 2022) requires officers to state the reason for a stop before questioning. AB 46 itself, in the 2023–2024 session, dealt with a military income tax exclusion and did not pass; the 2025–2026 version addresses criminal diversion programs.
The Actual Exhaust Noise Limit
Two statutes work together. Section 27150 requires every registered vehicle with an internal combustion engine to have a working muffler at all times, with no cutouts or bypasses.1California Legislative Information. California Code VEH 27150 The requirement is broad: if the muffler doesn’t prevent excessive or unusual noise, the vehicle is out of compliance whether or not anyone runs a decibel meter.
Section 27151 sets the concrete number. It prohibits modifying an exhaust system in a way that amplifies engine noise beyond the limits set elsewhere in the code, and it prohibits driving a vehicle modified that way. For non-motorcycle vehicles with a manufacturer’s gross vehicle weight rating under 6,000 pounds, the ceiling is 95 dBA measured under the current SAE International testing standard.2California Legislative Information. California Code VEH 27151 At or below 95 dBA under that test, the exhaust complies with Section 27151. Above it, it doesn’t.
That 95 dBA figure covers most passenger cars, trucks, and SUVs. Motorcycles and heavier commercial vehicles have separate, lower limits in Vehicle Code Sections 27200 through 27207.
What Counts as a Modification
Section 27151 reaches any change to the exhaust system that increases noise output. Aftermarket mufflers, headers, catalytic converter replacements, and exhaust tip changes are all in scope. The statute also explicitly covers nonoriginal exhaust equipment.2California Legislative Information. California Code VEH 27151 A common misreading is that only the muffler itself matters, but the entire path from engine to tailpipe is subject to the rule.
How Noise Is Measured
The law calls for testing under the most current SAE International standard, which measures sound at a set distance from the vehicle under controlled conditions. An officer’s opinion that a car “sounds loud” is not the Section 27151 standard. Officers can still cite under Section 27150’s broader “excessive or unusual noise” language, which requires no decibel reading. The 95 dBA number in Section 27151 is a measurable safe harbor: pass the test and you comply with that section.
The Fix-It Ticket Path
Most exhaust citations fall under Section 40303.5 as correctable offenses. When an officer marks a citation correctable, you have a set period to fix the problem, prove the repair, and pay a $25 dismissal fee instead of the full fine.3California Courts. What to Do if You Got a Fix-It Ticket
The steps are straightforward. Bring the vehicle into compliance before the due date on the ticket, which for a Section 27151 citation means getting the noise level at or below 95 dBA for vehicles under 6,000 pounds GVWR. Have a law enforcement officer or other authorized person inspect the repair and sign the back of the citation as a certificate of correction. Then submit the signed ticket to the court listed on the citation along with the $25 fee.
The financial gap between the two outcomes is large. Without the correctable option, a loud or modified exhaust citation can carry a base fine around $193 to $197, which climbs to several hundred dollars once California’s mandatory state and county surcharges are added. The $25 route saves most drivers hundreds.
Whether the officer writes the citation as correctable is partly discretionary. The Vehicle Code authorizes correctable treatment for equipment violations but does not always require it. If you receive a standard citation for an equipment issue you think should have been correctable, you can raise that with the court.4California Legislative Information. California Code VEH 40150
If You Ignore the Ticket
Skipping a correctable citation is the worst outcome available. Miss the deadline to fix and submit proof, and the ticket converts to a standard infraction with the full fine. Late fees stack on top. Keep ignoring it, and the court can report a failure to appear, which can trigger a hold on your driver’s license and, in some cases, a bench warrant. A $25 problem turns into a suspended license and a fine of $500 or more quickly.
Points and Insurance
An exhaust citation is an equipment violation, not a moving violation. California’s DMV point system assigns points for things like speeding, running stop signs, and reckless driving. A pure equipment citation typically carries zero points, so it shouldn’t directly raise your insurance rates or push you toward a point-based suspension.
Two things can change that. If the same stop produces a moving violation alongside the equipment issue, the moving violation carries its own points. And if a fix-it ticket escalates into a failure to appear, the record consequences outrun the original equipment problem.
Officers Must State the Reason for the Stop
Since January 1, 2024, any California peace officer making a traffic or pedestrian stop must tell you the reason for the stop before asking questions about a possible crime or traffic violation.5California Legislative Information. California Code VEH 2806-5 The officer also has to record that reason on any citation or police report resulting from the stop. This rule came from AB 2773, not AB 46, and lives in Vehicle Code Section 2806.5.6California Legislative Information. AB-2773 Stops: Notification by Peace Officers (2021-2022)
There is one exception. An officer can withhold the reason if disclosing it would endanger life or property because of an imminent threat, such as an active kidnapping or terrorism situation.5California Legislative Information. California Code VEH 2806-5 Outside that narrow scenario, the reason should come before the questioning.
For an exhaust stop, the practical effect is documentation. If an officer pulls you over for a modified exhaust, that reason has to be stated upfront and written down. If the stated reason is a loud exhaust but the encounter shifts to something unrelated and no equipment citation issues, the gap becomes visible on the paperwork and can be raised in court.
Equipment-based stops remain legal. Officers can still pull you over for an aftermarket exhaust or any other Vehicle Code violation. What changed in 2024 is that the reason goes on the record.