What Happens if You Modify a Vehicle Before a Lemon Law Claim?

When you’ve invested in a vehicle, it’s natural to want it to reflect your personality and meet your lifestyle needs. But what happens when that same vehicle starts showing serious mechanical problems and you’re thinking about filing a lemon law claim? The question of modifications can quickly become a source of stress and uncertainty.

At the Law Offices of Kevin Faulk, P.C., our San Jose, CA lemon law attorney has spoken with countless drivers who worry that something as simple as an aftermarket part might cost them their rights under state law. Here, we’ll explain what to expect if you find yourself in this situation and offer some potential options for moving forward.

If you live in Sunnyvale, San Jose, San Francisco, Oakland, Sacramento, Bakersfield, Los Angeles, San Diego, or anywhere else in California, we’re here to provide clarity and guide you through your legal options. Reach out to us today to discuss your situation and learn more about how we can help protect your rights.

What California’s Lemon Law Covers

California’s lemon law is one of the strongest consumer protection laws in the country. It’s designed to give car buyers recourse when their new or used vehicle with a warranty can’t be repaired after a reasonable number of attempts. Before filing a claim, it’s helpful to know exactly what types of vehicles and situations are covered. The law applies to:

• New vehicles under warranty

• Used vehicles with a remaining manufacturer's warranty

• Cars, trucks, SUVs, motorcycles, and some business vehicles

If your car qualifies as a lemon, you may be entitled to either a replacement vehicle or a refund of the purchase price, including related costs such as taxes, fees, and incidental expenses. Before looking at the impact of modifications, it’s important to note that California’s lemon law only applies when the defect substantially impairs the vehicle’s use, value, or safety.

How Vehicle Modifications Can Affect a Lemon Law Claim

Modifying a vehicle doesn’t automatically prevent you from filing a lemon law claim. However, modifications can complicate the process by raising questions about whether the defect was caused by the manufacturer or by the changes made after purchase. Because of this, even small upgrades or cosmetic changes can sometimes become a point of contention.

When you file a claim, the manufacturer will likely review your car carefully. If they find aftermarket parts or customizations, they may argue that these changes contributed to the problem. For example, a performance chip that alters engine settings could be blamed for transmission failure, even if the issue is a known defect.

This makes it critical to separate manufacturer-caused defects from any impact modifications may have had. That’s where legal guidance becomes invaluable, helping you draw a clear line between your warranty rights and unrelated modifications. Having someone advocate for you helps keep the focus on the manufacturer’s responsibility.

Common Types of Vehicle Modifications

Car owners modify their vehicles for many reasons, from aesthetics to performance. While not all modifications will affect a lemon law claim, some are more likely to raise red flags with a manufacturer. Before deciding whether to move forward with a claim, it’s helpful to understand which types of changes are more likely to draw scrutiny.

• Cosmetic upgrades: Custom paint jobs, body kits, decals, or tinted windows usually don’t affect a lemon law claim unless the issue directly involves the modification (for example, improper tint causing electrical issues in window sensors).

• Audio and electronics: Upgraded stereo systems, alarms, or remote start installations may create wiring issues that a manufacturer could try to connect to broader electrical failures.

• Performance enhancements: Turbochargers, superchargers, performance exhausts, or chips that alter factory settings can be blamed for engine and transmission problems.

• Suspension and wheels: Lift kits, oversized tires, or lowered suspensions can affect steering, braking, or alignment, which complicates defect claims related to safety or drivability.

These examples highlight how the type of modification matters and why a manufacturer might try to use them as leverage in disputing your claim. While these changes don’t eliminate your rights under California law, they can create hurdles. Working with an experienced lemon law and auto fraud attorney is essential in this situation. Contact Kevin Faulk, P.C., today to get started.

Manufacturer Strategies When Modifications are Found

When a manufacturer sees modifications, they may attempt to deny or limit your claim. This doesn’t mean your claim is automatically invalid, but it does mean you’ll need to be prepared to address any arguments they raise. Understanding the tactics manufacturers might use can help you respond effectively and protect your rights. Here are some strategies they might use:

• Blame-shifting: Claiming the modification directly caused the issue, even if the defect is widespread among unmodified vehicles.

• Warranty void arguments: Suggesting your aftermarket changes voided part or all of your warranty, especially when performance parts are involved.

• Delaying tactics: Requesting additional inspections or repairs to argue that your case isn’t ready for resolution.

• Partial responsibility claims: Agreeing there’s a defect but insisting the modification worsened it, reducing what they’re willing to offer.

These strategies can be frustrating and discouraging. But it’s important to remember that modifications don’t automatically strip away your rights. With the right legal support, you can push back against unfair tactics and keep the focus on the manufacturer’s responsibility for defective vehicles.

What You Can Do if You’ve Modified Your Vehicle

If you’ve already made changes to your car and are facing ongoing problems, there are steps you can take to strengthen your potential lemon law claim. By understanding what documentation and evidence are most important, you can present a clearer case to the manufacturer. Here are some of the steps you can take:

• Document everything: Keep detailed records of your modifications, receipts, and installation notes, along with repair orders for the defect itself.

• Gather evidence of the defect: Show that the problem is unrelated to your modifications—for instance, citing recall notices or widespread reports of the same issue in unmodified models.

• Consult professionals: A qualified mechanic can provide an opinion on whether the defect is manufacturer-related rather than caused by your customization.

• Seek legal guidance early: Don’t wait until the manufacturer denies your claim. Legal support from the start can help you build a stronger case.

While modifications can complicate matters, proactive preparation can make a big difference in how your claim is received. Following these steps gives you a stronger position and makes it harder for a manufacturer to attribute the defect to your modifications. With careful preparation, you can keep the focus on the vehicle’s actual problems rather than the changes you’ve made.

Situations Where Modifications Typically Don’t Affect Claims

Not every customization will create a challenge in a lemon law case. In fact, many changes are so minor or unrelated to the defect that they’re unlikely to matter. Understanding which modifications are low-risk can help you make informed decisions. Being aware of these distinctions also makes it easier to explain your situation to the manufacturer or your attorney.

• Cosmetic-only changes: Custom paint, decals, or upholstery usually have no connection to mechanical or safety problems.

• Dealer-installed accessories: If the dealership installed the modification at the time of purchase, it’s generally considered part of the transaction and can’t be used to deny your rights.

• Aftermarket wheels or tires: Unless the defect involves alignment, suspension, or tire wear, these changes are often irrelevant.

• Upgraded audio or navigation systems: Most audio or infotainment modifications won’t impact claims about drivetrain, safety, or other unrelated systems.

Recognizing the difference between modifications that are relevant and those that aren’t can reduce stress and help you focus on the real issues. This clarity can also make your lemon law claim stronger and more straightforward to pursue. Being able to clearly explain which changes did or didn’t contribute to the problem can give you an advantage.

Speak With a Knowledgeable Lemon Law Attorney Today

It’s natural to worry that your decision to customize your vehicle might cost you the protection of California’s strong lemon law. But the truth is, you still have rights. Whether you’ve added aftermarket rims, upgraded your sound system, or even installed performance parts, what matters most is whether the defect is tied to the manufacturer’s workmanship.

At the Law Offices of Kevin Faulk, P.C., we’re committed to helping drivers in Sunnyvale, San Jose, San Francisco, Oakland, Sacramento, Bakersfield, Los Angeles, San Diego, and throughout California pursue justice. If your car has turned out to be a lemon, don’t let modifications stop you from exploring your legal options. Reach out to us today.