The Guide to Auto Parts Cross Reference

The Guide to Auto Parts Cross Reference

If Apple can use Samsung and LG screens for their iPhones, who’s to stop any other brand from utilizing other companies’ components? In fact, mass production is founded on the concept of sharing parts. Electronics, furniture, computer, and automotive industries depend on the opportunity to incorporate parts from other models or even brands into their new products. For an auto aftermarket retailer, auto parts cross reference features are integral to their operations.

The US Bureau of Transportation statistics declares that the average age of passenger vehicles is almost 12 years. These are relatively old vehicles that require regular repair, maintenance, and most likely replacement parts. A car owner who can’t find a part from a car like theirs will search for identical or compatible parts from other vehicles.  

To find compatible auto parts, vehicle owners have the option of visiting a junkyard (salvage yard), swap meets, or a dealer. They can also search for parts in online catalogs of various auto aftermarket stores – an option that is comfortable, convenient, and safe in these pandemic times. 

If you’re in the business of selling car parts online, this guide to auto parts cross reference will teach you everything you need to know to provide your customers with the best buying experience. 

Types of Car Parts

Even though there are many different classifications of car parts, two primary ones are the focus of our topic here: OE parts and OEM parts. 

  • OE Parts

OE is short for Original Equipment. An OE part is produced by the same manufacturer that assembled the vehicle; it is a genuine or original part of the vehicle that came out of the same factory. 

For example, BMW OE parts have BMW part numbers and original BMW packaging.

When looking for new parts, OE parts are the most expensive but also the highest in quality. You can’t go wrong with obtaining an OE part for your vehicle.

  • OEM Parts

As opposed to the genuine or original OE parts, OEM parts are considered replacement parts. OEM stands for Original Equipment Manufacturer. The original carmaker does not produce them. Instead, they are made by a company approved and authorized to manufacture parts for that specific vehicle make and model. 

BMW doesn’t produce their own suspension parts. This is the job of Thyssenkrupp, a company that is an accredited BMW supplier, manufacturing these parts that are invaluable for BMW cars. 

OEM parts are not as pricey as OE parts in the aftermarket industry, but they are also considered a high-quality and worthy replacement for OE parts. 

Benefits of Cross Referencing

Implementing cross-reference in your online catalog shouldn’t be left out in the initial stages of business development. It is an integral segment of operations that will benefit you, other businesses, and individual customers. 

  • Business Benefits

Complete and accurate fitment data will give you an edge over your competitors. Remember: if your website visitors don’t find the information they’re looking for, they will immediately go to a rival company. So having a mighty cross-reference tool is essential for retaining customers. 

But you don’t have to think only in terms of car owners. Your customers can also be other businesses, such as distributors, engineering agencies, and OEMs. They might want to use your tool to change vendors if a part is removed from production or find a supplier with a shorter lead time or lower expenses.

  • Customer Benefits

As mentioned above, searching for the right parts for your car online is incredibly convenient. You don’t have to leave the comfort of your home. It’s only a matter of a couple of clicks before you have the right information at your fingertips. 

A comprehensive parts interchange database allows your visitors to find replacement components quickly, no matter where they are. Thanks to your straightforward catalog and website design, they don’t have to wait long to find an alternative car part or one that is less costly. 

What car parts are interchangeable?

Two questions are regularly asked on the internet: “What car parts are interchangeable?” and “What cars share the same parts?”

A short, direct answer to both of these would be – all of them. Generally speaking, all car parts can be interchangeable, and all cars share at least some parts with other models and makes. 

Car companies like to reduce costs any way they can. Developing a new vehicle design, testing it, assembling it, and putting it into production is costly. A carmaker would like to get their new product to market as fast as possible – cutting R&D costs is an efficient way to achieve this. 

For example, some cars share the same engine. A Mercedes-Benz A180d has the same engine as some Nissan and Dacia cars. Smart Fortwo has an engine identical to Renault Twingo. (As a matter of fact, approximately 60% of the Fortwo is the same as the Twingo.) Subaru developed an engine that can be found in Subaru BRZ and Toyota GT86. 

Vehicles can share even entire platforms. A platform includes the design, production, and engineering specs of a vehicle. Toyota GR Supra and BMW Z4 share the same platform even though they don’t belong to the same car brand. 

Mazda and Ford even had a 20-year-long manufacturing cooperation agreement. They shared engines, car platforms, chassis and brake parts, and much more. Even today, Ford has a deal with Yamaha for the production of engines and sub-assemblies. 

All of that being said, it is far more common for small parts to be interchangeable. Door handles, fuel pumps, brake pads, spark plugs, filters, side mirrors, lights, etc. – if you take a look at 15 different cars, chances are that they share at least one component with a different model or make. 

How to Cross Reference Auto Parts

So, how do you cross reference auto parts? What does your business need to provide so that a customer can find the right interchangeable parts? 

Since the main subject here are online retailers and managing an online aftermarket parts catalog, it would stand to reason that you need to incorporate some cross-reference tool into your website. 

There are several crucial elements to this tool that you should consider. 

Fitment Data

First and foremost, any search begins with typing in the information you know. Your website should have a search tool where visitors can put in fitment information and get results about parts they can order and compatible parts. 

The data that your potential customer can provide should be the following: 

  • Make
  • Model
  • Year
  • Engine
  • Trim/Submodel
  • VIN (Vehicle Identification Number)
  • Part Number, and more

Fitment data represents information about a specific part of a vehicle. The more data a visitor types in, the more accurate results they should get. 

Out of all the points listed above, the part number and the VIN are the most specific ones. 

VIN is a series of 17 characters (numbers and capital letters) that are like a vehicle fingerprint. Every vehicle has a unique VIN which describes the vehicle manufacturer, specifications, and unique features. 

If you own a car manufactured before 1981, the VIN may be anywhere between 11 and 17 characters. These vehicles have limited data on them. 

Not every part has a number assigned to it, but if it does, this number offers the chance to pinpoint the part in any vehicle in the database. A part number has information about a part’s type, color, dimensions, shape, and other important details. 

Providing your visitors with the option to enter a partial part number is good practice. They may not get the precise results they’re looking for, but a partial number is a good starting point. Once they get their results, the customer can further use a filter option to narrow down their search. 

Filtering Results

Once a user receives a list of results, they should be able to filter them somehow. Your cross-reference tool should have filters such as the product type, manufacturer, and similar. Filters are typically designed as dropdown boxes, making it easy to select the ones the user wants. 

If a customer enters a partial number, they may get over 100 results. If they’re searching for an oil filter, they should be able to exclude all other part types from those results. 

When developing the cross-referencing tool, never lose sight of the customer and what their experience might be like.  

User Experience

Speaking of customer (or user) experience, your catalog and website should be presented in an easy-to-use way. Visitors don’t like spending too much time looking for the right button or text box – outline a clear path for them to how they can open your tool and start searching. 

User experience is crucial in application development, whether they are website, computer, or mobile device apps. You want as many customers as possible to visit your site, stay there long, and find what they need. 

Here are some ideas on how you might improve your user experience: 

  • Minimalist design without too many distractions on the landing page
  • Download button that allows your visitors to download their results
  • Mobile-device-friendly design – most people browse the web on their phones these days
  • Fast load speeds – don’t make your visitors wait too long to open a page or get their results

If you’re unsure of how to tackle all of this by yourself, hire a UX expert. These are usually designers with experience in building websites that people like to visit. 

Quality of Fitment Data

The core component of your entire business should be high-quality fitment data. High-quality data means that it is accurate, complete, and in the right format. 

  • Accuracy

Inaccurate fitment data can cause a range of problems for an online aftermarket retailer: bad reviews, customer dissatisfaction, expensive returns, and a nosedive in reputation. If your catalog information isn’t accurate, your customers will order and receive the wrong part. That is not a good outcome for anyone involved. 

Accurate data is the cornerstone of a thriving aftermarket business. 

  • Completeness

Incomplete data also leads to a loss of sales, though for a different reason. If a visitor on your website doesn’t find the information about a part they’re looking for, they will move on to a competitor. This is why it is essential to do your research on compatibility and keep a comprehensive collection of records. 

If you’re not offering all of the available information on your products, you are underselling them. Don’t allow your competitors to steal your customers away. 

  • Format

Lastly, the format of your catalog depends on the online marketplace your business is centered around. Amazon and eBay Motors require two different fitment data formats. Amazon asks for information formatted according to the ACES standard, while eBay needs it converted into MVL files. 

If you’re creating your own website and catalog, you should also look into the ACES and PIES standards. The MVL that eBay asks for isn’t too difficult to convert to, but it does require a few extra steps. Plus, the eBay format catalog can’t be used pretty much anywhere else. 


The Auto Care Association developed two types of data standards to attempt to standardize all auto parts data. They are the Aftermarket Catalog Exchange Standard (ACES) and Product Information Exchange Standard (PIES).


ACES represents a link between a specific vehicle and a part number. It includes all the data we outlined above, such as the vehicle make, model, year, part number, type, brand, and other information. 

An important segment of ACES is the Vehicle Configuration Database (VCdb). There, you can find over 60,000 configurations for all light, medium, and heavy-duty vehicles for sale in Canada, Chile, Colombia, Mexico, and the USA. The VCdb is updated every month – new configurations on the market are added regularly, while old ones get eliminated when they exit the market. 

ACES isn’t free – it requires a subscription to access. However, most aftermarket retailers in the automotive industry use this standard for their catalogs. 


ACES compiles data about part applications, but PIES deals with product data. Over 20,000 products are divided into 25 categories in the PIES database. 

Unlike the ACES, PIES doesn’t require a fee. However, some databases in connection with it demand a subscription much like the ACES does. PIES is also frequently updated with new information, and obsolete data is removed. 

Using ACES and PIES

These two ACA standards are meant to be used together. ACES can help an online seller decide whether a part is suitable for a specific vehicle. PIES can further determine whether these parts (or accessories) meet all the customer’s requirements. They contribute to the accuracy, completeness, and reliability of fitment data we emphasized above – your customers will greatly appreciate getting the right parts at the right time. 

You need to keep in mind that your inventory database needs to be kept up-to-date with the ACES and PIES. These standards can be complex, and it is time-consuming to validate your data against them constantly. Consulting a professional might be a good option for you until you get a handle on things. 

Catalog Holes and Spoiled Data

A ‘catalog hole’ is a place in the catalog where data is missing. It can happen if a component is labeled as belonging to a car whose configuration has been redefined or removed. It can also happen with custom-made parts that haven’t been logged into any database yet. In such cases, you might need to enter the part data manually. 

Another problem is ‘spoiled data,’ or data that isn’t regularly updated as ACES and PIES databases are updated. If fitment data sits for too long without following the new changes, it can become spoiled. 

When managing your online catalogs, avoiding catalog holes and spoiled data are vital to good business.


Parts interchange and compatibility is a hot topic in the automotive industry. Technically speaking, no car doesn’t share at least one component with a different car. You can find this even in electric vehicles – the Tesla Model Y and Model 3 share about 76% of the same parts! 

Offering compatibility lists and a cross-referencing tool on your website benefits your business, other businesses, as well as your customers. You need to consider all the fitment data a potential customer will enter, how they will filter their results, and the overall user experience of your marketplace or website. 

Above all else, your fitment data has to be complete, accurate, and formatted correctly. Using the ACES and PIES standards is the norm, and you would do well to familiarize yourself with these databases. Your catalogs should be free of holes and spoiled data, meaning you will have to update them regularly according to the ACES and PIES. It’s a lot to take in. If you’d like more information about auto parts cross reference or would like some help in setting up your online catalog, contact us at Illumaware. We would be happy to offer our expertise in evolving your business!