In California, the emissions warranty requires vehicle manufacturers to cover emission-related parts for 3 years or 50,000 miles on 1990 and newer passenger cars, light-duty trucks, and medium-duty vehicles, with extended coverage of 7 years or 70,000 miles for high-cost components.1California Air Resources Board. California Vehicle and Emissions Warranty Periods Zero-emission and plug-in hybrid vehicles carry their own longer terms, including separate battery protections that expand starting with the 2026 model year. The warranty transfers automatically to used-car buyers, and using an independent shop or aftermarket parts does not, by itself, void it.
The Two Warranties: Defects and Performance
California’s program has two parts, and which one applies depends on how the problem shows up.
The Defects Warranty covers any emission-related part that fails because of a flaw in materials or workmanship. You do not need to fail a Smog Check to use it. If the Check Engine light comes on because an oxygen sensor died prematurely or an EGR valve cracked, this is the warranty that pays for diagnosis, parts, and labor.2New York Codes, Rules and Regulations. California Code of Regulations Title 13 Section 2037.0.1
The Performance Warranty applies when the vehicle actually fails an official Smog Check inspection during the warranty period. The manufacturer must then make whatever repairs or adjustments are needed to bring the car into compliance with California exhaust standards. The trigger here is a failed test, not just a suspicious part.3California Air Resources Board. Title 13, California Code of Regulations Section 2035
How Long the Warranty Lasts on Conventional Vehicles
For 1990 and newer passenger cars, light-duty trucks, and medium-duty vehicles, both the Defects and Performance Warranty run for 3 years or 50,000 miles, whichever comes first.1California Air Resources Board. California Vehicle and Emissions Warranty Periods
On top of that, California requires an extended high-cost parts warranty of 7 years or 70,000 miles. If your vehicle fails a Smog Check after the standard warranty ends but before the 7-year/70,000-mile mark, and the failure traces to a part on the high-cost list for your vehicle, the manufacturer pays for the diagnosis and repair.2New York Codes, Rules and Regulations. California Code of Regulations Title 13 Section 2037.0.1
Which Parts Count as “High-Cost”
A component qualifies for the 7-year/70,000-mile coverage if it meets a cost threshold set annually by the California Air Resources Board using the Consumer Price Index. For the 2025 model year, that threshold is $770; any individual warranted part costing at least that much is treated as high-priced.4California Air Resources Board. Manufacturer Advisory Correspondence ECCD-2024-001 The 2026 figure had not been formally published at the time of writing and will be adjusted upward from CPI.
Parts that commonly clear the threshold include catalytic converters, turbocharger assemblies, and certain electronic control modules. Your owner’s manual lists which specific parts on your vehicle qualify. If your car is between 3 and 7 years old and something expensive fails, check that list before paying out of pocket.
Coverage for Electric and Plug-In Hybrid Vehicles
Transitional Zero Emission Vehicles, 2018–2025
Vehicles certified to the Transitional Zero Emission Vehicle (TZEV) standard for model years 2018 through 2025 carry a Defects and Performance Warranty of 15 years or 150,000 miles on all emission-related parts except the battery. The battery or energy storage device is covered separately for 10 years or 150,000 miles.1California Air Resources Board. California Vehicle and Emissions Warranty Periods
2026 and Newer Zero-Emission Vehicles
Starting with the 2026 model year, zero-emission vehicles certified under Advanced Clean Cars II fall under CCR Section 1962.8. Propulsion-related parts follow the conventional structure: 3 years or 50,000 miles for standard parts and 7 years or 70,000 miles for high-priced propulsion components. The battery rules are new. For 2026 through 2030 model year battery electric and plug-in hybrid vehicles, the manufacturer must warrant that the battery will maintain at least 70 percent of its certified state of health for 8 years or 100,000 miles. Starting with 2031 models, that retention floor rises to 75 percent.5California Air Resources Board. CCR Section 1962.8
Plug-In Hybrids Counting Toward the ZEV Mandate
For 2026 and later plug-in hybrids that manufacturers use to satisfy a portion of their annual ZEV requirement, the defects and performance warranty extends to 15 years or 150,000 miles.6California Air Resources Board. CCR Section 1962.4 – ZEV Standards 2026 and Subsequent Model Years
What Parts the Warranty Covers
The warranty covers every part whose primary function is controlling or reducing vehicle emissions. Specific components vary by vehicle, but the major categories include:
- Fuel metering system, including fuel injection components and air-fuel ratio control
- Exhaust gas recirculation (EGR) system, including the EGR valve and rate feedback controls
- Evaporative control system, including the vapor storage canister, fuel tank, and filler cap
- Positive crankcase ventilation (PCV) system, including the PCV valve and oil filler cap
- Ignition system components affecting combustion efficiency, including ignition coils and control modules
- Exhaust aftertreatment, including catalytic converters and related sensors
- Electronic controls, including the ECU, oxygen sensors, air-fuel ratio sensors, and the OBD device
- Connecting hardware: hoses, clamps, fittings, and tubing that link warranted parts
Your owner’s manual should include the complete list of warranted emission-related parts for your specific vehicle, including which ones meet the high-cost threshold for extended coverage.7California Air Resources Board. Emission Warranty Parts List
Aftermarket Parts and Independent Repair Shops
Getting service outside a dealership, or installing an aftermarket part, does not automatically void your emissions warranty. Two federal laws protect you.
The Magnuson-Moss Warranty Act bars manufacturers from conditioning warranty coverage on the use of dealer-authorized shops or manufacturer-branded parts, unless the manufacturer provides that service or part at no cost. An oil change at an independent shop or a non-OEM air filter is not grounds for denying an emissions claim.
The Clean Air Act adds an emissions-specific protection: a manufacturer cannot refuse warranty repairs simply because aftermarket parts are on the vehicle. The exception is when the aftermarket part itself caused the emissions failure. A non-certified exhaust modification that damages a catalytic converter can be denied. An internal defect in that same catalytic converter is still covered even if you have an aftermarket air intake bolted on elsewhere.8US Environmental Protection Agency. Aftermarket Defeat Devices and Tampering Are Illegal and Undermine Vehicle Emissions Controls
Tampering is the hard line. Removing, bypassing, or disabling any emissions control device violates federal and California law and voids the warranty. Aftermarket parts carrying a CARB Executive Order (EO) number have been tested and approved as not increasing emissions, and installing an EO-numbered part is the safest way to modify a vehicle without risking coverage.
Buying a Used Car: Does the Warranty Transfer?
Yes. California emissions warranties follow the vehicle. The regulations extend coverage to “the ultimate purchaser and each subsequent purchaser,” so buying used does not eliminate the remaining warranty.9California Air Resources Board. Title 13, California Code of Regulations Section 2036 – General Emissions Warranty Coverage A 4-year-old California-certified car with 55,000 miles still has 3 more years or 15,000 miles of high-cost parts coverage.
Coverage applies to vehicles certified to California emissions standards, which you can confirm on the Emission Control Label (ECL) under the hood.10California Air Resources Board. Engine Label or Emission Control Label (ECL) A vehicle bought in another state but originally certified to California standards still qualifies. A federal-only vehicle later registered in California does not receive California’s extended coverage, though its federal warranty remains.
Filing a Claim
Most claims start one of two ways: a Check Engine light or a failed Smog Check. Either way, take the vehicle to an authorized dealership for the brand.
For a Defects Warranty claim, you only need to present the vehicle with the reported malfunction. The manufacturer covers diagnosis, parts, and labor. For a Performance Warranty claim, bring a copy of the official failed Smog Check report, since this warranty is tied to that failure.
If the manufacturer wants to deny the claim, the burden of proof is on them. Under CCR Section 2037, the manufacturer must show that the vehicle was abused, neglected, or improperly maintained, and that this abuse or neglect directly caused the part to fail.11Cornell Law School. California Code of Regulations Title 13 Section 2037 A missing oil-change receipt is not, on its own, enough to walk away from a claim. Keeping your maintenance records is still worth the effort, because it heads off the argument entirely.
If Your Claim Is Denied
If a manufacturer or dealership denies your claim and you think the denial is wrong, California gives you places to push back.
CARB runs a warranty dispute mediation process. You can contact CARB at 1-800-242-4450 or helpline@arb.ca.gov to request that the Executive Officer mediate the dispute under CCR Section 2041.12California Air Resources Board. CCR Section 1962.8 – Mediation of Warranty Dispute
The Bureau of Automotive Repair (BAR) also mediates complaints between consumers and repair shops, including disputes involving Smog Check inspections and warranty repairs. Complaints can be filed through BAR’s online form, and a representative typically responds within 7 to 10 business days.13Bureau of Automotive Repair. File a Complaint
Past-Warranty Repair Help
If your vehicle has aged out of coverage and fails a Smog Check, California’s Consumer Assistance Program (CAP) may help with repair costs. Income-eligible owners (household income at or below 225 percent of the federal poverty level) can qualify for up to $1,450 in repair assistance for 1996 and newer vehicles, or up to $1,100 for 1976–1995 models. You must be the registered owner, the vehicle must have failed a biennial Smog Check, and the emissions control system must not have been tampered with.14Bureau of Automotive Repair. Apply for Repair Assistance It is worth knowing about even if you expect the warranty to apply, since many drivers do not realize their vehicle has aged past the coverage window until they are already holding a failed inspection report.