#BuyingGuide #B2B
How to Source Auto Parts by Part Number (and Write an RFQ)
A part number is the fastest way to start a search, but it does not tell you whether the supplier has the correct application, the exact unit, or physical stock. This guide is the process we use for international B2B sourcing: from the complete number to a quotation you can actually compare.
1. Start with the complete number
Record the number exactly as provided. Do not shorten it: part numbers carry application and revision information. 16790-5PC-H02, 16790-5LA-A01, 06161-59B-305, and 16790-59B-003 are four different references, even when two components perform a similar function.
| Information | Why it matters |
|---|---|
| Complete part number | Prevents incorrect search results |
| Manufacturer | Separates OEM and aftermarket references |
| Part description | Identifies the component type |
| Quantity | Determines stock and quotation requirements |
| Vehicle | Helps confirm application |
| Destination country | Shipping and market differences |
If some information is missing, do not invent it. Start with the confirmed number and ask for the missing details.
2. Determine who owns the number
Not every part number belongs to the same numbering system. A reference may come from Honda, Toyota, an OE manufacturer, an aftermarket manufacturer, or a distributor's internal catalog. Before comparing two numbers, determine which organization issued each one.
A vehicle-maker OEM number and an independent manufacturer reference can identify related components without being the same type of number. That distinction prevents the common mistake of treating every number found online as an equivalent OEM reference.
3. Identify the component before comparing price
“Honda fuel pump” is too broad. The vehicle could use an in-tank fuel pump, a fuel pump module, an engine-mounted high-pressure pump, a fuel pressure sensor, or a feed component. These are different parts. The same problem occurs with injectors, sensors, and ignition components.
Your request should contain both the part number and the component description. If you only have the number, ask the supplier to confirm the description before quoting.
4. Check whether the number is current
Manufacturers replace older service numbers with newer references. That does not mean the old number was wrong; it means the manufacturer now supplies a different reference. Honda, for example, lists 06161-59B-305 as a replacement for 16790-59B-003 for applicable vehicles.
Search both references: a supplier may hold stock under either the old or the current number. But a replacement relationship still has to be checked against the vehicle application.
Ask one precise question: “Is this the exact requested part number, or an official replacement?” Do not let a supplier silently substitute a different number.
5. Confirm the vehicle application
Even with a correct part number, fitment should be checked when the application is uncertain. Useful information: VIN, model, model year, engine, engine code, body style, trim, and market.
You do not always need every item. The more complex the application, the more information you should provide. VIN confirmation is especially useful when multiple numbers are possible, the vehicle has been imported, the model has several engines, the customer cannot identify the original part, or a high-value component is being ordered. A VIN is an additional verification layer, not a substitute for the part number.
6. Ask whether the supplier has physical stock
“We can supply it” and “we have it in stock” are different statements. A supplier may be able to obtain a part after receiving your order. That is not automatically a problem, but you need to know which situation applies before promising delivery to your customer.
Ask: “Is this item physically in stock now?” Then ask for the available quantity, stock condition, packaging condition, and estimated dispatch time. For urgent repair orders, this can matter more than a small difference in unit price.
7. Request actual product photos
A catalog image shows what the product is supposed to look like. An actual stock photo shows what the supplier currently has. Ask for photos of the product, part-number label, manufacturer markings, packaging, quantity, and batch or identifying information where available. A few clear images are usually enough; for high-value or unfamiliar inventory, ask for more.
8. Separate genuine, OEM, and aftermarket
Do not use these terms as if they mean the same thing.
- Genuine — sold as a genuine component from the named vehicle or manufacturer brand.
- OEM — used differently by different sellers; ask who manufactured the component and how it is supplied.
- Aftermarket — produced as a replacement rather than sold as the original branded part.
- Compatible — intended to replace another component; it does not automatically mean manufactured by the original brand.
If your customer specifically requested a genuine branded component, state that requirement before receiving the quotation.
9. Compare more than the unit price
| Check | Supplier A | Supplier B |
|---|---|---|
| Exact P/N | Yes / No | Yes / No |
| Genuine / OE status | — | — |
| Physical stock | Yes / No | Yes / No |
| Actual photos | Yes / No | Yes / No |
| Available quantity | — | — |
| Lead time / MOQ | — | — |
| Warranty terms | — | — |
| Unit price | — | — |
The lowest unit price is not automatically the lowest-cost option. A wrong part creates return freight, customer complaints, installation delays, lost labor, dead inventory, and international shipping costs.
10. Write an RFQ that gets comparable quotes
A weak request says “Please quote Toyota injectors.” A useful RFQ tells the supplier exactly what you need, how many, which product tier, and where it must go. Use the same RFQ for every supplier you compare.
| RFQ field | Example |
|---|---|
| Manufacturer | Toyota |
| OEM P/N | Complete part number, including suffix |
| Component | Fuel injector |
| Brand requirement | Genuine OE |
| Quantity | 20 pcs initial; 50–100 pcs monthly |
| Vehicle / application | Model, year, engine, VIN if available |
| Stock requirement | Confirmed physical stock only |
| Destination | Country / city |
| Shipping | Courier / air / sea; required timing; Incoterm if relevant |
| Verification | Actual photos, batch information, packaging |
Ask each supplier to quote the same fields: exact reference, brand, product type, confirmed quantity, unit price, packaging, lead time, freight, country of origin, photos, and warranty or return terms. Otherwise one quote includes freight, another excludes it, and a third quietly offers an aftermarket equivalent.
Five habits to avoid: “Please quote this” with no quantity or product requirement; “Toyota injector” with no part number; “OEM quality” with no product category; “Need urgently” with no destination or date; and “Same as last time” with no previous reference.
If you provide an older number, write: “If this part number has been superseded, please provide the current reference and explain the relationship.” That is much safer than “Please give me an equivalent.”
11. Keep the sourcing record
Save the information once the part is verified: requested P/N, current or reference P/N, manufacturer, vehicle, supplier, quantity, stock confirmed, actual photos received, fitment confirmed, and order date. This may seem unnecessary for one unit; for repeated distributor orders it becomes the sourcing trail.
When the supplier proposes a different number
Do not immediately accept or reject it. Ask what the relationship is, then classify the answer:
| Relationship | What it means |
|---|---|
| Official supersession | New reference replaces an older reference |
| Cross-reference | Another catalog identifies a corresponding reference |
| Aftermarket replacement | A different manufacturer offers a replacement |
| Similar application | May fit, but needs verification |
| Unknown | Do not assume interchangeability |
If you only have a photo
A clear photo can start the search. Ask for several views: the full component, label, stamped numbers, connector, mounting points, and packaging if available. Do not treat visual similarity as proof of fitment. If identification cannot be confirmed from the photo, ask for the VIN or the original part number. Mark the identification as pending rather than guessing.
A 60-second inquiry checklist
- Complete part number
- Manufacturer or vehicle brand
- Part description
- Vehicle model, year, engine, VIN if available
- Required quantity
- Destination country
- Genuine / OE / aftermarket requirement
The more complete the request, the less back-and-forth is required.
How we handle part-number requests
YUDI works primarily with Honda and Toyota parts and uses a verification-first process: send the part-number list → check availability and sourcing → photograph actual stock → buyer confirms → ship. We distinguish physically available inventory from parts that need to be sourced after the inquiry, and provide actual product and packaging photos where available.