Is It Illegal to Put a Supercharger on a Car?

Generally, no—it’s not inherently illegal to install a supercharger. However, it becomes illegal if the modification violates emissions, safety, or registration rules where you drive. In the United States, a supercharger can be street-legal if the vehicle still meets federal and state emissions standards (and has a CARB Executive Order in California and other CARB-adopting states), passes inspections, and is properly disclosed to your insurer. Other countries often require inspections or engineering approvals before the car can be used on public roads.

What the Law Actually Regulates

Lawmakers typically don’t ban “superchargers” as a concept—they regulate the consequences of modifications. The following factors determine whether a supercharged car is legal to operate on public roads.

• Emissions and tampering: In the U.S., the federal Clean Air Act prohibits tampering with emissions controls. Similar anti‑tampering rules exist in Canada and many other jurisdictions.
• Certification and approvals: California and several states that follow its emissions rules require a CARB Executive Order (EO) for emissions‑related aftermarket parts. In parts of Europe and Australia, formal approvals and inspections (TÜV, engineering certificates) are often required.
• Inspections: Your car still has to pass periodic checks—OBD readiness, visual inspections for emissions equipment, safety tests, and sometimes noise tests.
• Safety and engineering: Some regions require engineering assessment and certification when adding forced induction, especially if the vehicle wasn’t originally supercharged.
• Insurance and disclosure: Insurers often require you to declare performance modifications; failure to do so can invalidate coverage.
• Noise and nuisance laws: Even if emissions are legal, excessive noise or leaks can render the car noncompliant.
• Registration details: Significant engine changes may require updates to registration records or tax classification in some countries.

If your supercharger install preserves emissions controls, meets inspection standards, and satisfies local certification and insurance requirements, it’s typically legal to drive on public roads.

United States: How to Stay Street‑Legal

If you’re in the U.S., these steps help ensure a supercharger installation complies with federal and state rules.

1. Choose an emissions‑compliant kit: Prefer kits with a CARB EO number if you live in California or a state that follows California’s rules. Elsewhere, select kits marketed as emissions‑compliant and designed to retain factory emissions equipment.
2. Retain all emissions controls: Do not remove or defeat catalytic converters, oxygen sensors, EGR/EVAP systems, or secondary air systems. The tune must not disable OBD monitors or readiness checks.
3. Get professional tuning and documentation: Use a reputable tuner who can supply calibration details and, ideally, emissions‑friendly maps. Keep invoices and dyno or emissions test results.
4. Check inspection requirements: Know your state’s OBD, visual, and safety inspection rules. Confirm that readiness monitors set and there are no diagnostic trouble codes or visible tampering.
5. Notify your insurer: Declare the modification so coverage isn’t denied after a claim. Premiums may change.
6. Keep proof on hand: Carry the CARB EO certificate (where applicable), receipts, and any engineering or inspection certificates.

Following these steps won’t guarantee approval everywhere, but they align your build with the most common legal requirements and reduce the risk of failing an inspection or violating anti‑tampering laws.

Warranties and “Off‑Road Use Only” Labels

In the U.S., installing a supercharger doesn’t automatically void your warranty. Under the Magnuson‑Moss Warranty Act, a manufacturer can deny warranty coverage only for failures caused by the modification. That said, drivetrain failures plausibly linked to added boost can be excluded from coverage.

Parts labeled “for off‑road use only” are not legal on public roads simply because of the label. The EPA and state regulators consider such parts illegal for street use if they defeat emissions controls or cause the vehicle to exceed emissions limits, regardless of marketing language.

Other Regions at a Glance

Rules vary worldwide, but the through‑line is the same: keep emissions and safety intact, obtain required approvals, and disclose modifications.

• California and CARB‑adopting states (U.S.): Require a CARB EO for emissions‑related aftermarket parts to pass smog checks. Visual inspections often verify that emissions systems remain in place.
• United Kingdom: Modifications are legal if the car remains roadworthy and passes MOT (including emissions). Declare changes to your insurer; significant alterations may require an IVA test, and engine changes should be reported to the DVLA.
• European Union (e.g., Germany): Many parts need TÜV approval (ABE/Teilegutachten). Modifications must be inspected and documented in the registration to remain road‑legal.
• Australia: State‑based rules typically require an engineering certificate (e.g., VSB 14 guidelines) when adding forced induction to a previously naturally aspirated engine, with compliance to Australian Design Rules (ADRs).
• Canada: Emissions test programs vary by province, but federal anti‑tampering rules under CEPA still apply. Disclose modifications to your insurer; some provinces have safety inspections for registration or resale.
• New Zealand: Many performance modifications, including superchargers, require Low Volume Vehicle (LVV) certification before road use.

Always check your local transport authority’s guidance before you buy parts; approval pathways and paperwork can be specific to your jurisdiction and vehicle.

Common Ways a Supercharger Install Becomes Illegal

Most legal issues arise not from the supercharger itself but from how it’s installed and tuned. Watch out for these pitfalls.

• Removing or hollowing catalytic converters, or deleting EGR/EVAP systems.
• Tunes that disable OBD readiness monitors or turn off malfunction indicators.
• Lack of a CARB EO where required, even if the car seems to run clean.
• Fuel leaks, inadequate crankcase ventilation, or excessive intake/exhaust noise.
• Skipping mandated engineering/roadworthy certifications in regions that require them.
• Failing to disclose the modification to your insurer or finance company.

A compliant hardware setup paired with a conservative, emissions‑friendly tune and proper documentation will avoid most of these problems.

Summary

Installing a supercharger isn’t automatically illegal. It is legal in many places provided the vehicle still meets emissions and safety standards, you follow local approval and inspection processes (such as CARB EO in California or engineering certification in Australia), and you inform your insurer. The fastest way to get into trouble is by defeating emissions equipment or skipping required approvals. When in doubt, choose an emissions‑compliant kit, keep all emissions systems functioning, use reputable tuning, and verify local rules before you bolt anything on.