Last reviewed: 3 October 2026

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Can modifying my vehicle void the warranty?

For aftermarket and recycled parts, the FTC says your warranty stays in effect. The manufacturer or dealer can still deny coverage for a part that a defective or badly installed part damaged, but it must prove the cause. The FTC page does not cover other kinds of modification.

What the FTC means by the terms

The FTC says "An aftermarket part is a part made by a company that didn’t make your vehicle." It says "A recycled part is made for and installed in a new vehicle, then removed and made available for resale or reuse."¹ A warranty, in the FTC's words, is "a promise to fix certain defects or malfunctions during a specific timeframe after you buy a vehicle."¹

What the FTC says, step by step

1. Using aftermarket or recycled parts does not by itself end your warranty. The FTC says the warranty "stays in effect."¹
2. If a defective part, or a part installed incorrectly, damages a part the warranty covers, the manufacturer or dealer can deny coverage for the damaged part and charge you for repairs.¹
3. Before denying coverage on that basis, the manufacturer or dealer must prove the aftermarket or recycled part caused the damage.¹

In plain words (our summary): the question for a denial is what caused the damage, not only whether a non-original part is on the vehicle.

Parts that the warranty may require you to use

The FTC adds a limit. If the warranty says the work will be done for free, "the dealer or manufacturer can make you use repair facilities it chooses."¹ If the warranty says you will get parts for free, "the dealer or manufacturer can require you to use parts it chooses."¹ Our guide independent repair shops and your warranty covers the underlying federal rule in more detail.

A purchased service contract is different

The FTC says an auto service contract "is not a warranty as defined by federal law, because you buy it separately."¹ The FTC statements about aftermarket and recycled parts above are made about the warranty. The FTC page does not say how they apply to a service contract. Read your contract's exclusions; see reading a vehicle service contract's exclusions.

Keep records

Records of what was installed, by whom and when can help show what caused a problem. The FTC advises keeping records of repairs and maintenance.¹ See maintenance records and warranty claims.

Where this fits our standard

Point 1 of our standard asks whether contract terms and exclusions are disclosed in plain language. The Register reports how we check providers by category. It describes a method, not a recommendation of any company.

How to verify this yourself

• Open the FTC page (reference 1) and read "Facts About Auto Warranties." Every statement above comes from it.¹
• Read the warranty booklet for what it says about parts, repairs and modifications.
• If a claim is denied on the ground that a part caused damage, ask the dealer or manufacturer what it says caused the damage. That follows from the FTC's statement that it must prove the cause (our suggestion, not the FTC's).¹

What this page is not

This is general information from an FTC consumer page, not legal advice. It does not say whether a particular modification affects your coverage or whether a claim should be paid. It covers aftermarket and recycled parts only. It does not cover state law or emissions-related rules.

What to do next

Before you add a part, read your warranty booklet and keep the receipt and installer details. If a claim is denied because of a part, ask what the manufacturer says caused the damage. Start from the vehicle warranties hub.