OE number and manufacturer number: not the same thing

Anyone looking for a spare part faces two numbers that look interchangeable and are not. Understanding the difference is what separates a correct order from a return.

The OE number

OE stands for *Original Equipment*: it is the number the car maker uses to identify that part in its own parts list. `1K0 615 301 AA` is a Volkswagen number; `77 01 207 484` is Renault.

The OE number does not say who made the part. It only says that this car maker fits it under that number. The same part can be sold under different OE numbers by different brands of the same group.

The manufacturer number

It is the number of the part maker: `09.9468.11` is Brembo, `0 986 479 R33` is Bosch. Often the maker that supplies the car manufacturer also sells the same part in the aftermarket, under its own number and in its own box.

A part with a manufacturer number and one with an OE number can come off the same production line. What changes is the box, the sales network and, often, the price.

Why a part has many numbers

• Supersessions. When the car maker changes a component, the old number is replaced by a new one. Usually the new one also fits older cars, not always the other way round: the car maker decides, case by case.
• Cross-references. Each part maker states which OE numbers its part corresponds to. That is how you get from the number read on the removed part to a spare you can buy.
• Markets. The same part can have different numbers in Europe and elsewhere.

How to check before ordering

1. Read the number on the fitted part, if it is legible. It is stamped or on a label.
2. Compare the measurements, always. For a brake disc: diameter, thickness, height, number of holes. Two discs for the same model with different diameters mean that model was built in more than one version.
3. Check the chassis number, if the part depends on the trim level. On many cars the choice changes during production, and the year of first registration is not enough to tell.
4. Be wary of equivalences that do not cite a source. A compatibility stated by the part maker counts; one deduced from a copied list does not.

A typical case

The same car model can have different braking systems depending on the engine or trim: for example front discs of different diameters. The pads look alike at first glance and in many catalogues they appear together under the same model.

Anyone who orders by model and year alone risks taking the wrong one. Comparing the disc diameter and the number on the removed part greatly reduces that risk. If you are in doubt, write to us with the number you read on the part: we will check it before you order.

This advice is general: for the part numbers and measurements for your car, refer to the manufacturer's data.