Internationally Standardized Parts Numbering Systems

In the automotive parts trade, part numbers serve as a component's "ID card," acting as a key tool for cross-language and cross-regional communication. Sellers should focus on two main types of numbering systems: Original Equipment (OE) numbers assigned by automakers and Aftermarket (AM) numbers used by parts manufacturers or distributors. Understanding these codes helps accurately match parts to vehicle models, reducing communication errors.

Meaning and Role of OE Numbers

An OE (Original Equipment) number is a unique identifier assigned by an automaker to its genuine parts. Every component used in vehicle assembly carries this number, assigned by the OEM (Original Equipment Manufacturer) according to its parts catalog system. OE numbers typically consist of a combination of letters and digits, with varying formats depending on the manufacturer.

For example:

• Toyota parts numbers often follow a "5-digit–5-digit" format (e.g., 90915-YYYXX for an oil filter).

• Volkswagen Group (VAG) part numbers usually contain at least 9 characters, logically grouped—the first three often indicate the applicable model or engine. For instance, parts starting with 1H0 typically fit the Golf Mk3 (chassis code 1H). This numbering logic was designed by Ferdinand Porsche in the 1930s and is still used in German car parts today.

For sellers, mastering OE numbers is crucial:

• A single OE number may correspond to multiple supplier-made replacement parts for the same vehicle.

• Buyers often search or inquire using OE numbers to confirm compatibility.

• Including OE numbers in product listings significantly improves search accuracy.

• When buyers provide a VIN (Vehicle Identification Number), sellers can cross-check it against OE catalogs to ensure correctness.

Notably, many globally renowned parts manufacturers (e.g., Bosch, Denso, Delphi, TRW) supply both OE and aftermarket parts. Their products may carry both the OE number and the manufacturer’s own part number. For example, a Bosch spark plug might display both Bosch’s reference number and the corresponding OE number from the automaker.

Aftermarket (AM) Numbers and Common Rules

Aftermarket (AM) numbers are product codes assigned by parts manufacturers or distributors in the replacement parts market. Since AM parts come from various suppliers, their numbering systems lack standardization. Thus, the industry commonly uses OE cross-referencing to manage compatibility—indicating which OE numbers a given AM part can replace.

This cross-reference mechanism is widely used in parts databases and software:

• In Europe, sellers can use TecDoc to input an OE number and find compatible AM parts from different brands.

• In North America, the AutoCare Association’s ACES/PIES standard helps match parts to vehicles.

While AM numbers lack a global standard, some categories follow de facto conventions:

• Collision parts (e.g., bumpers, headlights) in North America use Partslink numbers for insurance claims and procurement.

• Standardized parts (e.g., spark plugs, bearings) often adopt industry-standard codes (e.g., NGK spark plug numbers directly indicate size and heat range).

In short, AM part numbering primarily serves a "many-to-one" mapping: multiple brands’ replacement parts correspond to a single OE part.

Key Takeaways

• OE numbers = Automaker-assigned, ensure exact OEM fitment.

• AM numbers = Manufacturer-specific, require cross-referencing with OE codes for compatibility.

• Cross-referencing tools (TecDoc, ACES/PIES) help sellers match AM parts to OE standards.

• Some parts (e.g., spark plugs, filters) follow industry-standard numbering, simplifying identification.

Understanding these systems helps sellers improve part matching accuracy and meet buyer expectations in global markets.