Short answer: the OEM number is the part number the vehicle manufacturer assigns to each part. To find it, you first identify the exact vehicle (by license plate or VIN) and then locate the part in the exploded view of the manufacturer's catalog. With that number you can look up the original part or an equivalent alternative in your stock, without guessing.
What OEM means
OEM stands for Original Equipment Manufacturer. In auto parts, it refers to the parts and part numbers defined by the vehicle's brand: the OEM number of a brake pad is the number that brand uses to identify that pad for that vehicle.
It's the common language of the industry. Two stores may call the same part by different names ("control arm", "wishbone", "A-arm"), but if they share the OEM number, they're talking about the same thing.
Original, aftermarket and cross-references
- Original part: the part sold by the vehicle's brand under its OEM number.
- Aftermarket part: a part from another manufacturer made to replace the original. It usually has its own number, but states which OEM number it's equivalent to.
- Cross-reference: the link between the OEM number and the aftermarket numbers that replace it. It's what lets you offer the customer an original option and a cheaper one for the same vehicle.
That's why the OEM number is the starting point even if you mostly sell aftermarket parts: it's the key to finding the right cross-reference.
How to get to the right number
1. Identify the vehicle without ambiguity
The same model and year can have different engines or trims, and many parts change depending on that. Start with the license plate or the VIN; in our article on how to identify the vehicle before quoting we explain what each detail tells you.
2. Locate the part in the exploded view
Parts catalogs organize the vehicle by system (engine, brakes, suspension, body) and show each system in an exploded view: a diagram with numbered parts. Seeing the image helps confirm it's the part the customer is asking for, especially when they describe it in their own words ("the rubber piece under the shock absorber").
3. Check whether the number has changed
Manufacturers sometimes replace a part number with a new one for the same position. If you search your stock with an old number, you may say "I don't have it" while the part sits in your warehouse under the new number.
4. Cross-check with your stock
With the OEM number (and its cross-references), you look up in your ERP or online store what you have, at what price and in which warehouse. Only then do you quote.
Why it's the step that takes the most time
Finding the number depends on the salesperson's experience: knowing which catalog to search, reading the exploded view and recognizing the part from how the customer describes it. It's valuable know-how, but when everything goes through the same person, every quote waits its turn. And as we saw in how to quote faster, delays cost sales.
How Partsflow does it
Victor, the agent that quotes, finds the OEM number with the exploded view and shows your salesperson the catalog image, the similarity score and the source, so they can check it in seconds. Then he quotes with the price, stock and purchase link from your own catalog. At the start, your team approves every quote before it goes out.
The part-number finder covers light vehicles; it does not cover trucks.
To see how it works with your parts, see what an AI agent for auto parts does or book a 20-min demo.