Is It Dangerous to Buy a Car with Aftermarket Parts Installed?

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It's not always possible or practical to buy or lease a new car. Sometimes, you're faced with having to purchase a used automobile. While this process may seem straightforward, searching for the right used car is a lot different from picking a new one off of the lot. There is one critical thing to consider when looking into a used automobile, and being aware of this prior to purchase could save you a lot of time and headaches in the future.

Is it dangerous to buy a car with aftermarket parts installed?

The answer is yes, in some cases it can be dangerous to purchase a vehicle with aftermarket parts installed by a previous owner or unqualified shop. However, there is a fine line between cars modified in a safe way and ones that are modified in an unprofessional or illegal manner. Some parts can increase the value of the vehicle to the right buyer, and others can lead to trouble and reliability issues later on. This is why it is good to be informed about aftermarket parts and modification.

Here are a few aftermarket parts commonly installed on used vehicles to gain fuel economy and horsepower, yet may interfere with emissions laws or reliability of the vehicle:

  • Cold air intakes: These are commonly installed due to an advertised increase in fuel economy and slight increase in horsepower. Cold air intakes are unnoticeable by the average driver. One upside is that many replace the factory filter with a re-washable and reusable lifetime filter. They can let in more dust than factory filters and in some cases, cause a check engine light or failed emissions test due to improper installation of the mass airflow sensor.

  • Performance mufflers/Exhaust systems: These are advertised to increase horsepower and give the vehicle a more aggressive sound. It is good to know whether a sound changing muffler has been installed or if the entire exhaust system has been replaced with a reliable and state emission legal brand. If the exhaust system or muffler is missing emissions equipment such as the oxygen sensor or catalytic converter, the vehicle may be unsafe to drive and may not pass emission testing. Always check the installation receipts for a reputable brand and reputable shop. If the paperwork is not available, have a trusted mechanic take a look.

  • Supercharger/Turbochargers: Anytime a vehicle is equipped with a non-factory forced induction setup, there should be paperwork and/or a warranty provided by the owner to ensure the work was performed by a reputable source. Great caution should be taken with cars that have these hefty modifications, as they can be very powerful and safety equipment may need to be upgraded. Often, vehicles with these modifications are not street legal. Unless you are searching for a race car, stray from cars with these parts.

  • Aftermarket blow-off valves/intercoolers/gauges/shifters: On cars that come equipped with factory turbochargers, owners may have installed aftermarket turbo blow-off valves, boost gauges, or shifters. These aftermarket parts, if of good quality, can better the driving experience for some, and give the car a more crisp and responsive driving experience if installed properly.

  • Wheels/tires/suspension parts: A good set of wheels and a lower stance can make a car look great when done properly, but be prepared to spend more on tires and suspension parts over the course of ownership if the vehicle has a modified wheel alignment, or excess camber. Being low can also damage exhaust, crack front bumpers, and puncture necessary engine components such as the oil pan.

Keep in mind that while this short list of aftermarket parts and modification reveals the good and the bad of each common aftermarket part, it is up to you as the buyer to have a mechanic look at any parts you are unsure of. While having a nice set of wheels and aggressive exhaust may increase the value to the right buyer, in many cases the trade in value decreases significantly. This is because the general attitude is that unmodified vehicles are more valuable. Always be aware that aftermarket parts can be illegal, and can be very dangerous if tampering with the emission system has occurred.

When looking at a vehicle, there may be clues that the vehicle has had aftermarket modifications. These clues include:

  • A louder than normal muffler
  • A cone-shaped air filter
  • A suspension that looks altered
  • Mismatched paint, such as near a spoiler or bumper
  • A different steering wheel

Many aftermarket parts can improve the car’s performance, but it’s important that buyers are aware of those modifications, and that they were installed correctly. If you suspect that your car has had aftermarket modifications, a pre-purchase inspection can help make sure that everything is in proper working order.


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Ben

39 years of experience
1113 reviews
Ben
39 years of experience
Toyota Camry - Pre-purchase Car Inspection - Houston, Texas
Ben was professional and extremely thorough with the pre-purchase inspection. He was able to recognize and find issues that were not disclosed by the seller. His extremely thorough report allowed me to negotiate better after my findings and get a better deal. Ben was on time and friendly. He is very knowledgeable and was up front about everything. I would definitely recommend him if purchasing a new vehicle and will use him again if services are needed.
Lexus ES350 - Pre-purchase Car Inspection - Spring, Texas
Ben was absolutely professional and right to the point. Ben pointed out discrepancies about my Lexus honestly... I definitely will call upon Ben if any work needs to be done to my Vehicles. An Awesome Mechanic..

Torrieanto

10 years of experience
473 reviews
Torrieanto
10 years of experience
Jeep Wrangler - Pre-purchase Car Inspection - Largo, Florida
Torrieanto did a fantastic job on a used car pre-purchase inspection. He was very thorough and took the time to explain the technical details and ramifications to me. He also gave me peace of mind with my purchase and a few negotiating points to further reduce the purchase price.
Lexus IS200t - Pre-purchase Car Inspection - Tampa, Florida
Went above and beyond. Really took his time and was very professional. Great customer service. Thank you!

Gus

15 years of experience
16 reviews
Gus
15 years of experience
Audi A6 Quattro - Pre-purchase Car Inspection - Arlington Heights, Illinois
Gus was great! He talked with me before and after he did his inspection and was very informative. He walked me through what he checked and what he recommended to replace/service on the vehicle for optimal performance. I would definitely recommend him!
Chevrolet Camaro - Pre-purchase Car Inspection - Elk Grove Village, Illinois
My experienced with Gus was great. He was very personable, friendly, knowledgeable, professional, friendly, and knowledgeable.

Jose

8 years of experience
2 reviews
Jose
8 years of experience
Hyundai Genesis Coupe - Pre-purchase Car Inspection - Chicago, Illinois
Jose was right on time, listened to what I had to say about the car’s history. He did a thorough inspection on the car and pointed out the necessary adjustments for a healthier car. Would definitely need his services for the next project.

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