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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Jason

14 years of experience
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Jason
14 years of experience
Toyota Corolla - Pre-purchase Car Inspection - Jamaica, New York
I recommend Jason. I know little about cars and needed him to check out a car for me. Jason did a pre purchase car inspection for me. He explained what looked good and what looked to be of concern about the car. If it was a concern, he explained what needed to be done to get the car in good shape before the purchase. He had all the equipment to check out the car. I would book him again for any other services as he knows what he's doing and is friendly.
Kia Rio - Pre-purchase Car Inspection - Brooklyn, New York
Jason did a thorough job inspecting a car I was considering buying and answered all my questions after the inspection

Willie

23 years of experience
38 reviews
Willie
23 years of experience
Toyota 4Runner - Pre-purchase Car Inspection - Cerritos, California
Williec was definitely professional.and I would use his services again.He is very honest and was very thorough with inspecting the vehicle I purchased.Thank you Willie.
Mitsubishi 3000GT - Pre-purchase Car Inspection - Long Beach, California
Mechanic was professional and knowledgeable about cars. His recommendation was excellent and appreciated. I would definitely recommend this mechanic to others.

Attila

18 years of experience
566 reviews
Attila
18 years of experience
Volvo XC70 - Pre-purchase Car Inspection - Plainfield, New Jersey
Attila was very throughrout with the inspection of the car and confirmed my suspicions about the breaks
Volkswagen Jetta - Pre-purchase Car Inspection - Englewood, New Jersey
Mr. Attila is very knowledgeable about cars and he gave me good advice for future reference. Very kind and nice!

MICHAEL

32 years of experience
164 reviews
MICHAEL
32 years of experience
Ford Fusion - Pre-purchase Car Inspection - Huntingdon Valley, Pennsylvania
Michael was enjoyable to talk to. He gave me an honest, non-bias opinion of the vehicle I was considering buying. I was an out of state buyer, so having someone to rely on was important. I loved the pictures and the audio he included in his report, it was through. He pointed out a few things the dealer failed to bring up. Because of him I am deciding to move forward with the "deal"

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