Last reviewed: 30 September 2026

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The federal emissions warranty: what a carmaker must cover, and for how long

By federal law, a manufacturer must warrant a new light-duty vehicle's emission controls for 2 years or 24,000 miles, and specified major emission control components for 8 years or 80,000 miles, whichever comes first — at no charge, and separate from any warranty or service contract you buy.

Why it matters

A failed emissions part can be expensive, and for these parts federal law, not a contract you chose, sets a minimum period the maker must stand behind them. Knowing that legal floor helps you tell what you already have from what someone may be trying to sell you — the same distinction we draw in extended warranty vs. manufacturer warranty.

The two kinds of emissions warranty

• The defect warranty. The manufacturer must warrant that the vehicle or engine is designed, built and equipped to conform at the time of sale with applicable regulations, and is free from defects in materials and workmanship which cause it to fail to conform with those regulations for the warranty period (§ 7541(a)(1)).¹ In EPA's rule the defect periods are two years or 24,000 miles for light-duty vehicles, light-duty trucks and medium-duty passenger vehicles, and eight years or 80,000 miles for the listed components (§ 85.2103(d)(1)).²
• The performance warranty. If the vehicle fails an EPA-approved emission test during its useful life and that leaves the owner facing a penalty or sanction (including denial of the right to use the vehicle) under local, state or federal law, the manufacturer must fix the nonconformity at no cost to the owner. The periods are 24 months or 24,000 miles for light-duty vehicles, 8 years or 80,000 miles where a specified major component failed (§ 85.2103(c)(1); see also § 7541(b)).²¹

What the two lists say

The statute itself names three specified major emission control components: a catalytic converter, an electronic emissions control unit, and an onboard emissions diagnostic device, and lets EPA designate others that meet stated conditions.¹ The regulation's list is not a substitute for the statute's: the statute names an onboard emissions diagnostic device, which the regulation's list does not repeat. EPA's 2024 rule preamble describes those three items as identified by Congress in section 207(i)(2) and its own designations, such as gasoline particulate filters and the high-voltage battery components of electric and plug-in hybrid vehicles, as additions.⁶ Check both texts. This page covers light-duty vehicles; heavy-duty and medium-duty periods differ and are not described here.

What can defeat a claim

• Skipped maintenance. A manufacturer may require evidence only of maintenance it has an objective reason to believe was not performed and that could be the cause of the problem (§ 85.2104(b)). It may deny a claim over maintenance only if you cannot supply the evidence it requests, or it can prove the vehicle failed because of abuse, an instruction performed in a way that left a component improperly installed or adjusted substantially outside specifications, or unscheduled maintenance that removed or disabled an emissions-affecting component. It may not deny a claim over an uncertified part, or an unperformed instruction, that is not relevant to the reason the vehicle failed (§ 85.2104(g)–(h)).³
• Aftermarket parts. No valid performance warranty claim may be denied because of a properly installed certified aftermarket part. A manufacturer may deny a performance claim over an uncertified part only if it can show the part caused the failure, in a written explanation with stated elements (§ 85.2105).⁴
• Not a general breakdown warranty. Coverage is tied to defects that cause a failure to conform with emission regulations; the statute does not turn it into coverage for every failure.¹

How a claim works

You may submit a claim by bringing the vehicle to any repair facility authorized by the manufacturer to service that model, or authorized to perform emission performance warranty repairs (§ 85.2106(b)). The manufacturer must give a final decision within a reasonable time, not to exceed 30 days from when the vehicle is first presented or within the period you must repair it under law without further penalties (whichever is shorter), unless you request a delay or an event not attributable to the manufacturer or repair facility causes it; it must either say it will honor the claim or explain a denial in writing; and it bears the costs of a valid claim (§ 85.2106(d)–(g)).⁵

Practical steps

1. Check your vehicle's warranty booklet for its emission-warranty section and compare its mileage and years with the periods above.
2. Keep service records. Under 40 C.F.R. § 85.2104 a manufacturer may ask for evidence of maintenance it has an objective reason to think was skipped and could be the cause, and may deny a claim only on the grounds that section lists.³
3. Ask the authorized facility to put any refusal in writing, and ask the manufacturer for its written explanation if a claim is denied.
4. Before buying an extended plan, compare what it would add to this baseline; see reading a service contract's exclusions and recalls vs. known-defect exclusions.