What is covered under an emissions warranty?
An emissions warranty covers components that process a vehicle’s exhaust and clean it before releasing it into the environment. These components include:
- Catalytic converters
- Engine control modules (ECM)
- Exhaust gas recirculation (EGR) valves
- On-board diagnostic (OBD-II) systems
- Oxygen sensors
- Vacuum hoses and sensors in the exhaust system
Emissions coverage can also vary by state. California has stricter environmental standards for emissions than the federal government and other states. As a result, emissions warranty coverage and terms may be different for cars sold in California.
How long is an emission warranty good for?
Coverage terms in an emission warranty vary by component. Most emissions-related parts are covered for two years or 24,000 miles, whichever comes first. However, some major components, like the catalytic converter and emissions control module, have coverage for up to eight years or 80,000 miles.
What’s not covered under an emission warranty?
Like other auto warranties, emissions warranties have some exclusions written into the contracts for certain things that they don’t cover.
Some common exclusions for emissions coverage are:
- Damage caused by aftermarket parts or modifications
- Damage resulting from improper vehicle use
- Damage caused by lack of routine maintenance
- Damage from sources like car accidents or theft that is covered under a car insurance policy
- Regular maintenance services like oil changes, fluid flushes and inspections
Federal vs. state emissions warranties
In the U.S., all new vehicles must meet federal regulations for emission warranties set by the Environmental Protection Agency (EPA). However, the state of California has its own standards for emissions warranties that go beyond federal requirements.
The following table shows the comparison between the two:
| Federal emissions warranty | California emissions warranty | |
|---|---|---|
| Basic coverage | Covers most emissions-related components for 2 years or 24,000 miles | Covers most emissions-related components for 3 years or 50,000 miles |
| Extended coverage | Covers major emissions-related parts, such as the catalytic converter and engine control unit, for eight years or 80,000 miles | Covers a specific list of more expensive emissions-related parts for 7 years or 70,000 miles as well as the federal 8-year/80,000-mile coverage for major parts |
| Partial Zero-Emission Vehicles (PZEVs) | Standard federal emissions warranty applies | Provides coverage for up to 15 years or 150,000 miles for vehicles designated as PZEV |
| Geographic application | Applies to all light-duty cars and trucks in all 50 U.S. states | Applies to all new vehicles sold in California and in the following other states: Conn., Maine, Md., Mass., N.J., N.Y., Ore., Pa., R.I., Vt. and Wash. |
How to make a warranty claim
If you get an emissions warning light in your vehicle or it fails an emissions inspection while it’s under the emissions warranty, you can have it repaired at no cost.
Follow these steps to file a claim:
- Get a diagnostic report that details the specific failure.
- Schedule an appointment with a dealership authorized by your vehicle’s manufacturer. (It doesn’t have to be the dealership where you bought your vehicle.)
- Bring the diagnostic report along with your registration to the dealership so that it can verify warranty eligibility.
- Allow the service technicians to diagnose the issue and find a solution.
- Have your vehicle repaired as soon as possible and ask the technicians to inspect your emissions system once again after the repair work is complete.
Don’t wait for inspection failure
If your check engine light comes on during the warranty period, have it diagnosed quickly — emissions-related problems are covered under warranty.
What to do if your emissions warranty claim is denied
If the service center at the dealership refuses to repair your vehicle under the emissions warranty, you have a few options: One is to take your vehicle to another dealership for the same manufacturer. Another is to appeal the decision.
Here are the steps you should take to file an appeal:
- Request a written denial from the dealership, signed and dated.
- Contact customer assistance for your vehicle’s manufacturer and inform them of the denial. You may get faster results by contacting a regional office than the national headquarters.
- File a complaint with your regional EPA office detailing the issue and the denial.
- Reach out to your state’s consumer protection office and inform them of the issue.
Under federal law, dealerships are required to service eligible claims under warranty. Keeping detailed records of service appointments and communications will help you make your case.
Extending your emissions warranty coverage
You’re unlikely to find an extended car warranty for emissions components specifically. However, you can extend the coverage from your emissions warranty with a vehicle service contract, otherwise known as an extended car warranty. Many extended auto warranty plans include emissions components in their coverage.
There are two sources for extended auto warranties that cover emissions parts: your manufacturer and third-party providers. Manufacturer extended warranties, such as Mopar Vehicle Protection plans, require you to have all repair work done at licensed dealerships, just like the original factory emissions warranty. Most third-party extended warranties give you more choice over your repair facility, allowing you to have repairs done at any certified participating auto shop.
Emissions components aren’t usually covered on base-tier powertrain warranty plans. Mid-level plans may include coverage for your car’s emissions system, but plans vary by provider. Most exclusionary, or bumper-to-bumper, extended warranties will cover emissions-related parts.
FAQ
Is the catalytic converter covered under an emissions warranty?
Yes, the catalytic converter is covered under an emissions warranty. Catalytic converters are covered for eight years or 80,000 miles.
What happens if my vehicle fails an emissions test?
If your vehicle fails an emissions test, you won’t be able to pass inspection and renew your registration. You’ll need to repair your vehicle and pass the emissions test to be able to renew your registration and remain in compliance with the law.
Can aftermarket parts void my emissions warranty?
Yes, aftermarket parts can void your emissions warranty if they interfere with the normal functioning of your vehicle. Damage caused by aftermarket parts or modifications is usually named as an exclusion in emissions warranty contracts.
Are there any state-specific emissions warranty requirements?
Yes, some states have emissions warranty requirements that are different from federal requirements. California has its own environmental regulations that require three years or 50,000 miles of coverage for most emissions components compared with two years or 24,000 miles under federal rules.
California also stipulates warranty coverage of seven years or 70,000 miles for certain high-cost emissions components. Several states have adopted California’s emissions warranty requirements.
Article sources
ConsumerAffairs writers primarily rely on government data, industry experts and original research from other reputable publications to inform their work. Specific sources for this article include:
- North Carolina Consumers Council, “The Federal Emissions Warranty is Often Overlooked When Your Vehicle Needs Emissions Fixes.” Accessed Sept. 9, 2025.
