Q1 Doesn't the VC require a muffler on every vehicle?

Yes. Section 27150 VC requires that every motor vehicle subject to registration be equipped with an adequate muffler. There we no exceptions -- all vehicles must be equipped with a muffler, as defined in Section 425 VC A turbocharger is not considered a muffler.

Q2 Aren't 'I all exhaust system modifications prohibited?

No. Section 27151 VC prohibits the modification of the exhaust system to amplify or increase the noise emitted by the vehicle, making the vehicle not in compliance with Section 27150 VC or exceeding the noise limits established in Sections 27201-27206 VC. Section 27151 VC does not prohibit all modifications to an exhaust system. It also does not prohibit all modifications that increase the noise level of the exhaust system over that of the original, factory-installed exhaust system (as it did until 1980). It only prohibits modifications that result in a noise level higher than those specified In Sections 27201-27206 VC. Accurately determining compliance with Sections 27201-27206 VC for enforcement purposes is generally impractical. Enforcement personnel must make an informed professional evaluation to determine if excessive noise statutes are being violated.

Q3 Do I have to actually listen to a vehicle to cite it for a violation of either Section 27150 or 27151?

Yes. Drivers of vehicles should not be cited for violation of either Section 27150 or 27151 VC unless the officer has personally listened to the vehicle in operation. This can be either under actual driving conditions at with the vehicle stationary and the engine running. Even if the officer has inspected the exhaust system and does not see a muffler present, the officer should listen to the vehicle. The purpose of this is to be sure that the exhaust system does not incorporate internally baffled pipes or other components that meet the definition of a muffler. There are no specifications which state required configurations or minimum dimensions for mufflers. A vehicle that does not visually appear to be equipped with a muffler, but does not emit excessive noise, should be deemed to comply with Sections 27150 and 27151 VC.


Knox Letter | CHP Bulletin | Attachment 1 2 3 4
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