What does a vehicle corrosion warranty cover?

Short answer? Some forms of rust, some of the time.

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rust on exterior surface of vehicle

You might’ve noticed that your car came with something called a corrosion warranty in addition to your bumper-to-bumper and powertrain coverage. Corrosion warranties protect you against rust, which can literally eat away at your vehicle until it needs an expensive repair — or worse.

That’s why you should know what your corrosion warranty says and how to hold your automaker accountable if an issue at the factory causes your vehicle to rust prematurely.

But how do corrosion warranties work? What do they cover? And do extended auto warranties cover rust later in your vehicle’s life?

Read on to find out.

Key insights

  • Some corrosion warranties cover aluminum and iron body panels, but some only cover the latter. Others only cover perforation, which is rust so advanced it has created a hole in your car.
  • Most automakers include corrosion warranties with their new vehicles, and those warranties can still help people who buy used.
  • Extended warranties (also known as vehicle service contracts) generally do not cover corrosion.
  • To prevent corrosion, keep up with routine maintenance, including regular washes and waxes.

What is a corrosion warranty?

Broadly speaking, a corrosion warranty protects you from rust-related problems with your vehicle. If some part of the exterior of your vehicle starts rusting — like your brakes, undercarriage or body panels — your corrosion warranty may entitle you to a free repair at the dealership.

Automakers warranty their cars against corrosion in different ways.

Most new cars sold in the United States include some kind of corrosion warranty from the factory, ranging anywhere from three years/36,000 miles to 12 years (with no mileage cap). That means there’s a good chance you still have some of the corrosion warranty left if your vehicle is under 5 years old or has fewer than 60,000 miles. (And that’s true even if you bought your vehicle used. Factory warranties follow the car until they expire.)

» MORE: Car warranty guide: what you need to know

Unfortunately, not all factory corrosion warranties are the same when it comes to the fine details. Some cover “corrosion.” Others cover “rust.” And the remainder only cover “perforation.” Here’s what those terms mean:

  • Corrosion is a generic term for any chemical reaction that causes a material to deteriorate, whether it’s iron, plastic, aluminum or steel.
  • Rust is a specific type of corrosion that technically only applies to iron. If the language in your factory corrosion warranty specifies that it only covers rust, that means it may not cover corrosion to your aluminum body panels, for example.
  • Perforation is when rust gets so bad that it actually creates a hole somewhere in your vehicle. If your corrosion warranty only covers perforation (an “anti-perforation warranty”), then your manufacturer generally won’t cover your repairs until there’s a visible hole threatening the integrity of your frame or another component.

To determine whether your manufacturer’s “corrosion” warranty covers all perforation, rust or all types of corrosion, you often have to read the fine print in your warranty handbook.

» MORE: What does a car warranty cover?

What does a corrosion warranty not cover?

Every corrosion warranty is different, but one of the main things they have in common is that they don’t cover every kind of corrosion-related issue. Like it says in the subtitle, they cover some kinds of rust, some of the time.

Honda’s corrosion warranty is a great example of this. It only covers perforation that occurs from the inside out, meaning rust that bubbles up beneath the paint.

As a result, Honda’s corrosion warranty does not cover:

  • Surface rust on the underbody or anything that isn’t a body panel
  • Rusting of any body panels that weren’t replaced under the Honda warranty
  • Rust caused by:
    • Abuse, misuse or lack of maintenance
    • Damage (like from road debris)
    • Immersion in water, mud or sand
    • Exposure to corrosive gas or industrial fallout

Still, some corrosion coverage is better than none. Next, let’s have a look at how much corrosion coverage major automakers are offering these days.

Corrosion warranty coverage by manufacturer

While factory bumper-to-bumper warranties tend to be at least somewhat similar — ranging from three to five years in length — corrosion warranties are all over the place.

That can make a big difference, too. If you live somewhere with tons of salt in the air or on the road, you might seriously consider purchasing a vehicle with 12 years of corrosion coverage over one with just three.

Here’s a sample of a dozen major automakers and their corrosion coverage as of 2024.

Tips for getting corrosion warranty repairs approved

While corrosion coverage can be a literal lifesaver for your vehicle, drivers sometimes have trouble getting their warranty claims approved.

“Dealers will look for any reason to weasel out of a corrosion warranty repair,” said Sean Kim, an automotive technician in Atlanta. “For example, they’ll tell you you’ve got a water leak causing the issue, and that’s not covered.”

To improve your chances of getting your rust-related claim approved — and possibly prevent rust in the first place — consider the following tips:

  • Know your coverage: If your factory corrosion warranty only covers perforation for up to five years/60,000 miles, it’s probably not worth filing a claim for surface rust at 65,231 miles.
  • Keep up with regular maintenance (and save your receipts): One of the most common reasons warranty claims of all kinds are denied is that the owner didn’t keep up with maintenance. Sticking with the routine maintenance schedule listed in your owners manual (like getting oil changes every 7,000 miles or new brakes every 50,000 miles) is actually a requirement to keep your warranty coverage valid.
  • Wash your car at least once a month (and keep those receipts, too): While it may seem counterintuitive, car washes are actually excellent for preventing rust because they blast away salt, debris and other materials that can accelerate corrosion. Be sure to pay the extra few dollars for the undercarriage spray, as well, since that’s where most of the rust-causing agents will accumulate as you drive along.
  • Involve the manufacturer: If your local dealer is giving you the runaround, file a case with your vehicle’s manufacturer and request direct assistance from its customer care and/or warranty departments. The manufacturer may be able to influence the dealer’s decision or simply direct you to another dealership for the warranty repair work.

The good news is that most modern vehicles are heavily coated in layers of anti-rust protection, so the majority of drivers never need to worry about their vehicle rusting.

» MORE: How do you get your car warranty claim approved?

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How long are most corrosion warranties?

At the time of publishing, most manufacturers’ corrosion warranties last anywhere from three years/36,000 miles to 12 years with no mileage cap. Check your car’s warranty booklet to see how long yours lasts (many can be found online).

Is rust covered under a corrosion warranty?

Yes, but corrosion warranties don’t cover all forms of rust in all places. Some corrosion warranties only cover perforation, which is rust that has gotten so bad that it has actually created a hole in a part of your vehicle’s frame or body. Some warranties only cover perforation that occurs from the inside out, meaning it bubbles up inside the paint layer.

How much does rust on a car cost to fix?

We’d like to give a precise answer, but fixing rust can cost anywhere from $15 to thousands of dollars, depending on how bad it’s gotten and where it is.

On the low end, light surface rust can often be removed using WD-40 and painted over using a paint pen matching your vehicle’s exterior color code. On the high end, perforation of a structural component can require the entire thing to be replaced, costing well over $2,500.

Do extended warranties cover corrosion?

Generally speaking, extended auto warranties do not cover corrosion, rust or perforation.

In fact, rust is often a reason extended warranty providers deny coverage. For example, Omega Auto Care lists “any repair costs due to contamination of any kind, corrosion, rust” as an exclusion in its contracts.

In a similar vein, Endurance does not cover repairs for “damage and/or breakdown resulting from damage caused to an eligible component by impact or any other external force known or unknown, collision, bent or twisted parts, rust or corrosion.”

So, you’ll generally need to rely on your manufacturer’s corrosion warranty in order to get free rust-related repairs.

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