The EPA has a strict rule for commercial vehicles. Since 1988, any truck on American roads must not exceed 80 db(A) at a distance of 50 feet. This cap covers the entire exhaust system. The agency also bans the removal of any noise-reducing equipment. You can’t just strip parts off to get louder.
Yet, residents along busy highways often point fingers at engine brakes for the racket. Is it the compression brake? Sometimes. But often, it is the exhaust system itself. Many drivers are running improper setups that violate federal noise limits. This misconception has led to a wave of state-level legislation targeting commercial fleets.
Muffler Mandates and Heavy Fines
Several states have moved beyond general noise complaints. They now mandate that any vehicle with an engine compression brake device must have a functioning muffler. The penalty for skipping this? A $500 fine.
Montana was an early adopter. In 2003, Bill 237 required mufflers on all commercial vehicles equipped with engine brakes. Violators face misdemeanor charges. Colorado followed suit with House Bill 00-1142 in 2000. The rule is simple: if you have a compression brake, you need a muffler. Break that law and you pay $500.
This approach spread. A multistate highway transportation agreement saw Arizona, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington, and Wyoming adopt similar laws. They mirrored the Colorado statute. The result is a coalition of western states where engine brake noise is legally manageable through proper exhaust maintenance.
“Improper exhaust systems can be the problem, and many states are enacting legislations stating this.”
Why “Jake Brake” Signs Are Vanishing
The term “Jake Brake” is ubiquitous. It comes from Jacobs Vehicle Systems, the company that popularized the compression release engine brake. So ubiquitous, in fact, that highway signs in some regions used to explicitly ban “Jake Braking.”
But legal complications arose. Jacobs Vehicle Systems held copyright and trademark protections over the name. Using it in official government signage opened the door to legal issues. Many states had to pull those specific signs. They reverted to generic phrasing. Today, you see “Engine Brakes Prohibited” or “Brake Retarders Prohibited.” The slang died in the public sphere, even if the technology remains common.
If your local roads are plagued by diesel drone, check your state’s current statutes. The trend toward muffler mandates is clear. Contact local authorities and push for legislation that closes the loop on exhaust noise. The technology isn’t going away. The law just needs to keep up.
