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

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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Attila

19 years of experience
906 reviews
Attila
19 years of experience
Cadillac SRX V6-3.6L - Pre-purchase Car Inspection - Edison, New Jersey
Attila was great! Very knowledgeable and actually detected a fault during a pre-purchase inspection that would have cost me later.
Lexus ES350 - Pre-purchase Car Inspection - Fords, New Jersey
He is very good—offered all the significant details we needed from the inspection. Helped us figure out what needed to be fixed.

Shawn

12 years of experience
285 reviews
Shawn
12 years of experience
Chevrolet Impala V6-3.6L - Pre-purchase Car Inspection - Lansdale, Pennsylvania
Shawn was prompt, professional, and delivered the promised service as expected. This was a used vehicle pre-purchase inspection. Shawn also had to drive to multiple locations to perform the inspection, as the address listed that I provided him with was not accurate, but he still made it to the correct location within his time window and completed the inspection.
Toyota Sequoia - Pre-purchase Car Inspection - Akron, Pennsylvania
Shawn was very prompt in communicating with me and was good at helping me decide whether to purchase a used car. He help me avoid a car with a repaired rusted frame that could be a danger to my family's safety since we were planning on using the car to tow a travel trailer!

Luis

18 years of experience
320 reviews
Luis
18 years of experience
Honda HR-V L4-1.8L - Pre-purchase Car Inspection - Warren, New Jersey
Luis was great. He showed up on time, acted professionally, and gave me confidence with a pre-purchase car inspection.
Acura RDX - Pre-purchase Car Inspection - South Hackensack, New Jersey
Luis did a thorough pre-purchase inspection for me, and found several major issues that made me pass on buying the car. Had I purchased the car, I almost certainly would have ended up paying thousands in repairs down the road. Thanks Luis!

Robert

20 years of experience
1089 reviews
Robert
20 years of experience
Hyundai Elantra L4-2.0L - Pre-purchase Car Inspection - Englewood, Colorado
He did a pre-purchase inspection for me. He was knowledgeable and fast, and knew what he was looking for. I really appreciate all the pictures and documentation he took of the state of the car before purchase. He noted potential issues with the car that I wouldn't have been able to notice. Would recommend.
GMC Savana 1500 - Pre-purchase Car Inspection - Golden, Colorado
I trust Robert. He gave me a list and we will take care of it the week of June 29. I will know then that my vehicle is ready for the winter and is safe to drive. I look forward to getting things ready for another winter of careful driving.

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