Making modifications to a car can help improve its performance out on the road. Many car enthusiasts now choose to modify relatively new cars or classic cars to get better value from their vehicle. However, modifying your car can affect the warranty, which is something that stops many people from making helpful changes to their vehicles. 

Since cars are such a large purchase, many people rely on their warranties for peace of mind. If damage happens within the first few months after purchase, you’ll want to feel comfortable knowing that you can get your vehicle repaired. There has been plenty of confusion around how car companies address warranties for modified cars. Many drivers avoid aftermarket parts and other modifications out of fear that they won’t qualify for warranty service is they experience an issue with their car. 

However, there isn’t a one-size-fits-all approach to this situation. It depends on what type of car you have, how you modified it, and what exactly caused the damage to your car. Car companies go through a long assessment checklist to determine whether or not your warranty covers repairs. While this process differs slightly from company to company, here’s a general overview of how car manufacturers assess warranty eligibility for modified cars. 

What is a warranty and why is it so important? 

A warranty is essentially a contract with your car manufacturer that covers the cost of repairs to your vehicle if it is damaged within a certain time frame after purchase. A warranty is intended to protect the consumer financially - if the car is damaged right after purchase due to a manufacturing error, the warranty allows the consumer to take the vehicle in for repairs without any additional cost. Most vehicles come with warranties, and many car companies offer the option to purchase extended warranty coverage for even more security. 

Although you’re probably not thinking about repairs right after purchasing a new car, it’s still very important to consider the possibility and keep the warranty in mind when working on your car. There are certain circumstances that will void your warranty - for example, most warranties won’t cover any repairs if your car is totaled, and they won’t cover damage for misuse of the vehicle. In some cases, neglecting to maintain your car appropriately can also void your warranty. Understanding what your warranty does and does not cover is key when making a new vehicle purchase. 

Are your aftermarket parts covered? 

There are some instances where your warranty may specifically cover the addition of certain aftermarket parts to your vehicle. For example, some Ford vehicles have a Ford Performance warranty, which means that certain high-performance and racing parts from the brand are included in the warranty. If this is the case for you, your repair technician will confirm this before moving forward with other diagnostic checks. 

Could the damage have been caused by modifications?

In most cases, your warranty status will be determined by whether or not the modifications caused the damage. If you modified your car, but ultimately the damage was caused by an internal function that was already in place, then your warranty will likely still apply. If your repair technician suspects that damage was caused by installing an aftermarket part, they will look at specific data points and determine whether or not further investigation is needed. Some points they will look at include engine knock, instances of misfire, increased catalyst temperature, and air-fuel ratios. This information will indicate to your repair technician whether or not modifications have been made and if they could have caused damage. 

Has the car’s software been modified? 

One way that technicians will assess a car for aftermarket parts is to look at the software itself. The car’s software is an easy indicator of whether or not new parts have been installed. Many cars use ignition counters, which track the number of times the engine has started. These counters will usually reset to zero when aftermarket parts are installed. 

Is the damage internal? 

Your technician will then conduct a thorough audit to see if your car is damaged internally. Engine damage can come from a variety of sources, and isn’t necessarily an indicator of modifications. However, if the cylinder walls aren’t in good condition or the spark plugs have broken down, this could be an indication to your technician that the car has been modified and that continued investigation is needed. Internal damage isn’t always the result of modifications, so don’t panic if your engine isn’t in pristine condition - this doesn’t necessarily mean the warranty will be denied. 

Has the transmission been damaged? 

Another key factor that your repair technician will look at is the transmission. In particular, they will look at the torque converters to see if they have been modified for increased power. When high-power modifications have been applied to a car, they can wear out the torque converters faster, leaving visible spots of increased heat. Power modifications can also cause damage to the driveshaft and clutch, so your technician will also look at these key points. 

How can I avoid warranty denial? 

When putting any modifications on your car, it’s important to consider how they will affect the warranty. Keep in mind that auto professionals are very familiar with the possible modifications for many different types of cars. The auto manufacturers themselves may also specify certain modifications to look out for that could null the warranty. 

This doesn’t mean you should avoid modifying your car, but rather that you should be very careful with how you do so. When modifying, keep in mind what these car companies look at during warranty inspections, and take extra precautions to avoid damage. Be selective with the aftermarket parts you choose to install, as low quality parts are more likely to cause damage to your vehicle. They can also be a dead giveaway to your manufacturer that your vehicle has been modified if you do need to take it in for repairs. 

There are a few other things that will immediately give away a modification to a repair technician. The first is putting any kind of decal or sticker on your car that’s related to your modifications, whether that’s on the rear exterior of the car or on the dashboard. With a decal, you’re essentially advertising for your aftermarket parts company or modification shop.  

If you’ve already added aftermarket parts to your car, you may be tempted to quickly switch them back out for stock parts if you need to take the vehicle in for a repair. While this seems like an easy fix, it can backfire, so it’s something to avoid. In most cases, your repair technician will be able to tell how long the part has been in the car by the wear on it - or lack thereof. 

One of the best ways to avoid having your warranty denied is to stick to manufacturer-sanctioned parts when making your upgrades. Many car manufacturers have recognized the appeal of user modifications to their vehicles, and have adjusted their approach accordingly. Many car manufacturers produce a wide range of parts that can be used on their vehicles or sanction certain modifications from other aftermarket part manufacturers. 

Are modifications worth it? 

Upgrading your car is a big investment, so it’s important to make sure you’re spending money on parts that are really worth it. While the use of aftermarket parts won’t necessarily void your warranty, there is always the risk that you won’t get the coverage you need. Modifications should always be made with caution, and the benefits should outweigh the potential financial losses of voiding your warranty. 

On the other hand, if you really want to make a change to your car, the warranty shouldn’t be the only thing stopping you from doing so. Your warranty won’t be immediately voided with aftermarket parts - in many cases, you’ll still receive repair coverage as long as the parts themselves did not cause any damage. 

Certain types of modifications are more likely to be warranty-approved than others. Generally, car companies will accept modifications that alter the style of the car as long as they don’t offer the performance. That is why wheel upgrades, paint jobs, and interior upgrades are so popular - they allow you to tweak the way the car looks without actually interfering with its performance. 

When searching for a new car, it’s important to thoroughly research the warranty to understand what it does and does not cover. While you likely aren’t anticipating any problems with your vehicle at the time of purchase, it’s important to be prepared. If you’re interested in making extensive modifications that your warranty doesn’t cover, consider switching to a different model that has more of the features you are looking for.

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