Is it legal to remove a speed limiter in the US?

Generally, there is no blanket federal ban on removing a factory speed limiter from a privately owned passenger car, but doing so can become illegal if it involves emissions tampering, violates commercial-vehicle rules or employer requirements, runs afoul of state equipment laws, or circumvents restrictions on regulated devices like e‑bikes. As of late 2025, no federal regulation requires speed limiters on all passenger vehicles, and a nationwide mandate for heavy trucks has not yet been finalized; however, other laws and liabilities still apply.

What federal law does and doesn’t cover

Federal law does not currently require speed limiters on passenger vehicles, and the Federal Motor Vehicle Safety Standards do not set a maximum speed. The Federal Motor Carrier Safety Administration (FMCSA) has been pursuing a rule to require speed limiters on certain commercial motor vehicles, but as of late 2025 no final rule is in effect. That means there is not yet a universal federal requirement for limiters on trucks, though individual carriers frequently impose them by policy.

Where federal law is already clear is emissions. The Clean Air Act makes it unlawful to remove, bypass, or render inoperative emissions controls, including through engine-control module (ECM) “tunes” that disable onboard diagnostics, readiness monitors, or emissions strategies. Many methods used to “unlock” or alter a speed limiter involve ECU access and can unintentionally or deliberately change emissions-related calibrations—making on-road use illegal and subject to significant penalties. Even if a procedure purports to touch only the speed governor, if it impacts emissions systems or diagnostics, it’s unlawful for road use.

It’s also worth noting that defeating speed limiting technology on a vehicle you don’t own (for example, a rental, leased fleet, or employer-owned truck) can implicate contract violations and, in extreme cases, computer fraud or theft-of-services statutes, independent of traffic or equipment laws.

Commercial trucks, buses, and fleet rules

For commercial motor vehicles, the legal stakes are higher. Carriers often set governed speeds by policy, and tampering can violate employment agreements, safety policies, and federal safety responsibilities. If and when FMCSA finalizes a speed-limiter rule for certain trucks, removing or altering a required limiter would be a direct regulatory violation.

School buses and public-sector fleets frequently operate under strict policies—sometimes local laws—requiring limiters or intelligent speed assistance. Tampering in these contexts is typically prohibited and can lead to disciplinary action, contract termination, or citations under equipment or safety rules, even absent a specific state statute about “speed limiters.”

State law, inspections, and civil liability

Most states don’t mention “speed limiters” by name for private cars, but they do enforce broad equipment and emissions rules. Anti-tampering laws (often mirroring the federal Clean Air Act) prohibit altering emissions controls, and OBD-based inspections in many states will fail a vehicle with modified or disabled monitors. States also bar operating vehicles in unsafe condition; if a limiter removal results in noncompliant tires, brakes, or electronic safety systems operating outside design parameters, that can be cited.

Beyond statutes, removing a limiter can play into insurance and liability. If a crash involves high speed, a modification that enabled higher speeds can affect claim outcomes, subrogation, or litigation—especially if the change violated policy terms or contributed to the severity of the crash.

When removing a speed limiter is likely illegal

The following scenarios illustrate common situations where taking off or altering a speed limiter would violate law or contract, even without a nationwide passenger-car mandate.

• ECU/engine “tunes” that disable or alter emissions controls or OBD readiness monitors (Clean Air Act violations).
• Tampering with limiters on commercial vehicles where an employer requires them or where a future FMCSA rule applies once finalized.
• Defeating speed controls on rentals, leased fleet vehicles, or employer-owned vehicles against contract or policy.
• Altering limiters on regulated micromobility (e-bikes, e-scooters) to exceed class limits—illegal in many states and cities.
• Any modification that renders required safety equipment inoperative or the vehicle unsafe under state equipment laws.

In each case, the issue is less the abstract idea of “top speed” and more the legal environment around emissions, safety, and who controls the vehicle.

Risks even when it might be technically legal

Even if no specific law forbids removing a limiter on your private passenger car, there are practical downsides and legal exposures to weigh.

• Warranty and dealer support: Manufacturers can deny powertrain or related claims tied to unauthorized ECU changes.
• Insurance: Modifications that increase performance or risk may need to be disclosed; nondisclosure can jeopardize coverage.
• Inspection failures: Software changes can trigger OBD readiness issues leading to failed state inspections.
• Safety limits: Tires, brakes, and stability systems are engineered with speed assumptions; exceeding those can be hazardous.
• Civil liability: Post-crash investigations often analyze vehicle data; a removed limiter can be a factor in lawsuits.

These consequences can be costly even where criminal or traffic laws aren’t immediately implicated.

Special case: E-bikes and other micromobility

Derestricting an e-bike or scooter is a different legal landscape. Most states classify e-bikes by top assisted speed and motor power; removing a limiter usually changes the device’s legal class and can make it illegal to ride where e-bikes are allowed unless it is registered, insured, and treated as a moped or motorcycle. Similar rules often apply to shared scooters and city fleet devices, where tampering can also be a criminal offense.

How to check your situation before you modify

If you’re considering changes, confirm the legal and warranty implications first to avoid unintended violations.

• Review your owner’s manual and warranty guide for prohibitions on ECU or speed-governor changes.
• Ask your dealer or manufacturer whether a performance package or factory-authorized calibration exists.
• Check your state DMV and inspection requirements for emissions and OBD rules tied to software changes.
• Verify your insurance policy’s disclosure obligations for performance modifications.
• For commercial vehicles, obtain written authorization from the carrier; assume tampering is prohibited absent explicit approval.
• Monitor FMCSA announcements if you operate a CMV; rules may change once a speed-limiter mandate is finalized.

Doing this homework up front can prevent an expensive compliance or insurance problem later.

Bottom line

For private passenger cars, removing a speed limiter is not per se illegal under federal law, but it can quickly become unlawful if it involves emissions tampering or violates state equipment rules. For commercial and fleet vehicles, it’s often prohibited by policy now and could become a federal violation if an FMCSA mandate takes effect. Regardless, speeding remains illegal everywhere, and limiter removal does not legalize exceeding posted limits.

Summary

It is sometimes legal to remove a speed limiter on a privately owned passenger car, but only if the modification doesn’t tamper with emissions controls, contravene state safety or inspection laws, or breach contracts or policies. For commercial, fleet, and micromobility vehicles, limiter tampering is commonly prohibited and can be unlawful. Confirm federal and state rules, warranty/insurance terms, and—if applicable—carrier policies before making any change.