What Does OEM Mean?

oem parts
New parts can be OEM or something else. Matt Wright, 2015

Definition: OEM stands for Original Equipment Manufacturer

Does that clear it up? Probably not. Acronyms are funny like that. The real definition is easy to understand. OEM is usually used when referring to car or truck parts. If a part is called OEM, it was made by the manufacturer to be used in your car when it was new, and can be bought later to replace a broken part. For instance, if you drive a Ford, an OEM window switch was built by Ford to be used in your car.


What's not OEM

Usually OEM parts must be bought from a dealer or somebody who got the parts from a dealer or the manufacturer (that would be Ford in the above mentioned scenario). The window switch you see hanging on the rack in the auto parts store is not an OEM part, because it was manufactured by somebody else and only used to replace the window switch Ford installed on the assembly line. If you Google "2010 Ford window switch" you'll see results for a bunch of switches made by various companies to replace your switch. Usually you can't even figure out what that company actually is, but it doesn't matter because the $8 window switch is likely to give you $8 in service. That's not to say that there aren't some cheaply made parts out there that are completely serviceable. Generally, I apply the same logic to fake new parts as I do to what used parts are ok to use. If it's a complex electrical component, you may be very disappointed with what you get if you go the cheap route.

But if you're replacing a bumper, why not by a cheap one? There's always a compromise, but in many cases the money saved can be worth it. 

Since nothing is as simple as it could be, there's more. Sometimes Ford hires an outside company to produce all of their window switches for that year. In the case of an electrical part, they could outsource production to a high quality manufacturers like Bosch.

In this case, Bosch is the OEM supplier for window switches, and all of the switches they make for your car are therefore official Ford parts since they were installed on the assembly line. So they can sell Ford window switches later, under the Bosch name, and still call them OEM window switches, even if they were actually made years later. 

Automotive acronyms can be confusing. There are others, like NOS, OE, and POS. All of them have a specific meaning or serve a specific purpose in describing a car or truck part that you may or may not want to use to repair your vehicle.