What automotive replacement parts are and where to buy them
Automotive replacement parts are components you buy to fix or maintain a vehicle — anything from brake pads and air filters to alternators, door handles, and windshield wipers. You can buy them from dealerships (which sell parts made by the vehicle's manufacturer), independent auto parts retailers, online marketplaces, salvage yards, and sometimes directly from aftermarket manufacturers.
The main choice you face is whether to buy OEM parts (original equipment manufacturer — made by the company that built your car) or aftermarket parts (made by other companies). OEM parts cost more but are may provide to fit your exact vehicle. Aftermarket parts cost less but vary in quality depending on the brand. A third option is used or refurbished parts from salvage yards, which are cheapest but carry more risk.
Where you buy matters because prices vary widely for the same part, shipping times differ, and return policies are not the same everywhere. A part that costs $80 at one retailer might cost $120 at another, and some sellers will not take returns on electrical components or wear items like brake pads.
Key Takeaways
- OEM parts fit your vehicle exactly but cost more; aftermarket parts are cheaper but quality varies by brand and you should check reviews before buying.
- You need your vehicle's year, make, model, and engine size to search for the right part — mismatched parts will not fit or work correctly.
- Auto parts retailers, dealerships, online marketplaces, and salvage yards all sell replacement parts, and prices for the same part can differ by 30 to 50 percent.
- Return policies vary by seller, so check whether you can return a part if it does not fit or work before you pay, especially for electrical or wear items.
- Used parts from salvage yards are the cheapest option but come with no warranty, so use them only for non-critical components or when budget is the only factor.
Identifying the exact part you need
Before you search for a replacement part, you need to know what you are looking for. The easiest way is to look at the part that is broken or worn out — it usually has a part number stamped or printed on it. Write down that number and search for it directly. If the part is damaged beyond reading, take a photo of it and bring it to an auto parts store; staff can often identify it by sight.
You will also need your vehicle's year, make, model, and engine size. This information is on your registration, in your owner's manual, or on a sticker inside the driver's door jamb. Many online parts retailers have a search tool where you enter this information and the system shows you only parts that fit your vehicle. This step prevents you from buying a part that looks right but does not actually fit.
If you are not sure what part you need — for example, you know something is wrong but not what — describe the problem to an auto parts store employee or a mechanic. They can narrow it down. "My car is not starting" could mean battery, alternator, starter, or ignition switch; a mechanic can test and tell you which one is actually failing.
OEM parts versus aftermarket parts
OEM parts are made by the vehicle manufacturer or under contract to their exact specifications. They fit perfectly, are covered by the manufacturer's warranty, and are the safest choice if you are unsure. The downside is cost — OEM parts typically run 20 to 50 percent higher than aftermarket equivalents. For a brake pad set, that might mean $120 instead of $80. For an alternator, it could mean $400 instead of $250.
Aftermarket parts are made by independent companies and vary widely in quality. Some aftermarket brands are nearly as good as OEM and cost significantly less. Others are cheap for a reason — they wear out faster, fit loosely, or fail early. Before you buy an aftermarket part, read reviews from people who have actually installed it in your vehicle. Search "[your vehicle year/make/model] [part name] aftermarket reviews" to find real user experiences.
A practical middle ground: buy OEM for safety-critical parts like brakes, suspension, and steering components. Use aftermarket for wear items like air filters, wiper blades, and spark plugs, where the difference in quality matters less and the cost savings are real. For expensive parts like transmissions or engines, research the specific brand — some aftermarket remanufactured units are reliable, others are not.
Where to buy and comparing prices
Auto parts retailers like AutoZone, O'Reilly, Advance Auto Parts, and NAPA carry both OEM and aftermarket parts and usually have local stores where you can pick up same-day. Online retailers like RockAuto and Amazon often have lower prices but charge shipping and take several days to deliver. Dealerships have OEM parts and can order anything, but prices are highest and shipping can take a week.
Salvage yards (also called junkyards or auto recyclers) pull used parts from wrecked vehicles. A used alternator from a salvage yard might cost $50 versus $250 new. The trade-off is that used parts have unknown mileage and wear, come with no warranty, and may fail soon after installation. Use salvage yards for cosmetic parts (trim, mirrors, door panels) or when you are testing whether a part is actually the problem before buying new.
Price shopping is worth your time. Get the exact part number or description and search it at three to five retailers. You will often find 30 to 50 percent price differences for the same part. Online retailers are usually cheapest, but add shipping cost and delivery time to the total. If you need the part today, a local store is worth paying more for.
Understanding fitment and compatibility
The most common mistake is buying a part that looks right but does not actually fit your vehicle. This happens because many vehicles share similar body styles across years, or because a part number is close but not exact. A brake pad set for a 2018 Honda Civic will not fit a 2015 Civic, even though they look similar. An alternator for a 2.0L engine will not work on the same model with a 2.4L engine.
Always enter your vehicle's complete year, make, model, and engine size into the retailer's search tool before you buy. If you are buying from a salvage yard or private seller, confirm the donor vehicle's year and model match yours exactly. If the seller says "it should fit" or "it's close," do not buy it. Parts that are close do not work — they either do not fit at all or fit loosely and fail.
Some parts have multiple versions for the same vehicle depending on options. For example, a vehicle with a manual transmission might need a different clutch cable than one with an automatic. Check your owner's manual or ask the parts retailer to confirm which version you need before paying.
Return policies and warranties
Return policies vary significantly by seller. Most auto parts retailers accept returns within 30 to 90 days if the part is unused and in original packaging. However, many do not accept returns on electrical components, wear items like brake pads, or anything that has been installed. Some online retailers have strict no-return policies on certain categories.
Before you buy, check the seller's return policy. If you are unsure whether a part will fit, ask whether you can return it if it does not. Some retailers will accept a return even on an installed part if it is defective, but you usually have to pay return shipping. Others will not take it back under any circumstances.
Warranties on replacement parts are usually short — 30 to 90 days for most aftermarket parts, sometimes longer for OEM. Used parts from salvage yards typically have no warranty at all. If a part fails after the warranty period, you own the cost of replacement and labor to install it again. This is why buying from a reputable brand or retailer matters — you want recourse if something goes wrong.
Tools and information you will need before you start
Have your vehicle's registration or owner's manual handy so you can provide the year, make, model, and engine size accurately. If you are replacing a part yourself, check whether you need special tools. Some parts require only a wrench or screwdriver; others need a specialty tool that costs $50 to $200 or more. If you do not have the tool and do not want to buy it, factor in the cost of having a mechanic install the part.
Your owner's manual often has a parts diagram showing what components are in a system and how they connect. This is useful if you are trying to figure out what failed or if you need to understand how a new part connects. Many owner's manuals are available free online by searching "[your vehicle year/make/model] owner's manual PDF."
If you are buying a part to fix a specific problem, write down the symptoms — what the vehicle does or does not do, when it started, whether it is getting worse. This information helps a parts retailer or mechanic confirm you are buying the right thing. "My car will not start and the dashboard lights are dim" points to a battery or alternator; "my car starts but stalls when I stop" points to something else entirely.
Frequently Asked Questions
What is the difference between a remanufactured part and a used part?
A used part is pulled from a wrecked vehicle and sold as-is with no work done to it. A remanufactured part is disassembled, cleaned, worn components are replaced, and it is tested before sale. Remanufactured parts cost more than used but less than new, and usually come with a warranty. Used parts are cheapest but have no warranty and unknown history.
Can I return a part if it does not fit after I open the box?
Most retailers will not accept returns on opened or installed parts. Before you open the box, confirm with the seller that the part is correct for your vehicle. If you are unsure, ask the retailer's return policy — some will accept a return even on an opened part if it is defective, but you may pay return shipping.
Is it safe to buy used parts from a salvage yard?
Used parts are safe for non-critical components like trim, mirrors, door panels, and some mechanical parts like alternators or starters. Avoid used parts for safety systems like brakes, airbags, or suspension unless you have no other option. Used parts have no warranty, so if they fail, you pay to replace them again.
How do I know if an aftermarket part is good quality?
Read reviews from people who have installed the specific part in your vehicle. Search the part name and your vehicle year/make/model on forums and review sites. Look for reviews that mention how long the part lasted and whether it fit correctly. Avoid parts with many complaints about fit or early failure, even if they are cheaper.
What should I do if I buy the wrong part?
Contact the retailer when ready and explain the issue. If the part is unused and in original packaging, most retailers will accept a return or exchange. If you have already installed it, ask whether the retailer will accept a return anyway — some will if the part is defective or clearly wrong for your vehicle. Keep your receipt and packaging until you are certain the part is correct.