automotive aftermarket parts / Buying guide
OEM number cross reference: finding the part
An OEM number is the only unambiguous way to describe a part. A vehicle manufacturer assigns it, it identifies one component with one set of dimensions, and every serious aftermarket manufacturer publishes an interchange, or cross reference, to it.
The problem is that Chinese domestic listings are written for Chinese workshops, who search by vehicle model in Chinese, not by a European or Japanese OEM reference. The number is usually in the listing somewhere — it is just not what the listing is organised around.
In this guide
What the number tells you and what it does not
It tells you the exact component the manufacturer specified. It does not tell you that a Chinese factory makes an equivalent, that the equivalent holds the same tolerances, or that the seller listing it has ever seen one.
Aftermarket manufacturers publish cross-reference tables mapping their own part numbers to OEM references. Where one exists, matching is reliable. Where a seller has simply pasted a list of OEM numbers into a description to catch searches, it is worthless — and the two look identical on screen.
How to check a cross-reference is real
- Ask for the dimensions, not the number. A genuine supplier gives you bore, thickness, height, thread pitch. A reseller repeats the OEM number back at you.
- Ask which vehicles and which years. A real cross-reference covers a range and knows where it stops.
- Ask for a photograph of the part against a ruler. This catches the substituted-variant problem faster than anything else.
- Check the listed OEM numbers against each other. If a listing claims to fit forty unrelated OEM references, it is a search-term dump.
Where the fitment traps are
- Mid-year production changes. The same model year can take two different parts depending on build date or VIN range.
- Regional variants. A European and a Chinese-market version of the same car frequently differ in exactly the component you are buying.
- Left- and right-hand drive differences on anything steering, pedal-box or wiper related.
- Metric versus imperial threads on aftermarket fasteners and fittings.
What we do with a number you send
We search the Chinese domestic market by the OEM reference and by the component described in Chinese, which returns a different and usually larger set. We then ask the shortlisted sellers for dimensions and vehicle coverage in writing, and compare the answers against each other.
What you get back is the candidates, their dimensions, their prices and where they disagree with each other — because where two sellers disagree about a dimension, one of them is selling a different part.
Questions & answers
Common questions
- Can you find any OEM number?
- Most high-volume service parts, yes. Low-volume, model-specific or recently released parts often have no Chinese aftermarket equivalent, and we will say so rather than substitute something close.
- Will the part have the OEM number stamped on it?
- Aftermarket parts carry the manufacturer's own number. A part stamped with the vehicle maker's number and logo is either genuine or counterfeit, and at Chinese domestic prices it is not genuine.
- Do you supply genuine OEM parts?
- No. We source aftermarket and unbranded parts only. Parts bearing another manufacturer's mark are a legal risk we do not take on and do not pass to customers.
Your next step
Have a link you want checked?
Send a 1688 or Taobao product link and you get back the specification in English, the supplier check, and the landed cost to your country before you commit to anything.
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