How to find the correct part number for your car

Why the part number matters

The same model car can ship with different engines, gearboxes and trim packages — and each variant uses different parts. The part number (also called the OEM number or reference number) is the only reliable way to make sure the brake pad, filter or sensor you order will actually fit. Ordering by model alone is the most common reason returns and warranty claims fail.

1. Start with your VIN

Your Vehicle Identification Number is a 17-character code stamped on the dashboard at the base of the windscreen, inside the driver's door jamb, and printed on your licence disk. The VIN tells a parts catalogue exactly which factory build of your car you own, including engine code and production date.

• Snap a clear photo of the VIN plate so you can copy it without typos.
• Confirm the engine code on the cam cover or service book — VW, BMW and Mercedes engines especially.
• Note the production month/year from the licence disk; mid-year revisions are common.

2. Read the number off the old part

Whenever possible, pull the old component before ordering and look for a stamped or printed reference. Common formats:

• 1K0 615 301 AA — VW/Audi group format.
• 34 11 6 854 126 — BMW format.
• A 000 421 65 12 — Mercedes-Benz format.
• Bosch, NGK, Denso and other suppliers stamp their own reference too — both numbers help cross-reference.

Wipe the part with a cloth and use your phone torch. Numbers are often cast or stamped on a flat face and hard to read until the dirt comes off.

3. Cross-reference in an online catalog

Take the VIN and the number off the old part to a free catalogue to confirm fitment before you commit:

• 7zap, ETKA, RealOEM — exploded diagrams keyed to your VIN.
• TecDoc / PartsLink24 — aftermarket cross-references between OEM and brand part numbers.
• Manufacturer e-shops — VW, Toyota and Ford SA all expose a basic VIN lookup.

If two different numbers appear for the same part, that almost always means there was a running production change — pick the one whose date range matches your build month.

4. Confirm with the supplier before paying

On PartsBay every listing shows the supplier's WhatsApp. Send a quick message with your VIN and the part number you found — verified suppliers will confirm fitment in minutes and flag any newer revision. It is far cheaper than a return.

Quick checklist

1. Photograph the VIN.
2. Pull and clean the old part; record the stamped number.
3. Cross-reference VIN + part number in an online catalog.
4. Confirm with the supplier on WhatsApp before paying.