What does a Tier 1 or OEM buyer check before sourcing a new part from you?
They check your IATF 16949 status with the certificate number, the PPAP level you can submit, and whether you have process capability evidence. Automotive sourcing is a documented process, and a supplier who cannot show the documents cannot enter it whatever the part costs.
A sourcing engineer is assembling a bidder list that has to survive a supplier quality review.
Reviewed 4 August 2026
Scope and specifications
- Part families and processes
- The buyer matches their commodity to your process route.
- Materials and grades
- Determines feasibility and validation route.
- Annual capacity per part family
- Programme volumes are fixed; your capacity has to meet them.
- Tolerance and process capability
- Cpk expectations are explicit in automotive.
- Tooling capability and ownership
- Decides timeline and investment structure.
- Customer segments already supplied
- Tier 1, OEM and aftermarket are different qualification regimes.
- Plant locations
- Proximity and dual-sourcing are real sourcing criteria.
Documents buyers may need
| Document | What it proves | Where it belongs |
|---|---|---|
| IATF 16949 certificateAsked at: the first gate — usually before any technical review | The automotive quality system, with certificate number and certification body | Publish it |
| PPAP submission capability with levelAsked at: sourcing decision | That you can produce the production part approval package the customer requires | Publish it |
| Part Submission WarrantAsked at: part approval | Formal declaration that parts meet requirements | Per shipment |
| Control plan and APQP evidenceAsked at: supplier quality assessment | That quality is planned into the process, not inspected in | Name it, share on request |
| SPC and Cpk dataAsked at: technical review | Demonstrated process capability on the characteristics that matter | Name it, share on request |
| IMDS submission capabilityAsked at: onboarding | Material data reporting into the automotive industry system | Publish it |
| Run-at-rate or capacity studyAsked at: before programme award | That the quoted volume is achievable at the quoted quality | Name it, share on request |
Details for a useful enquiry
- Part drawing and customer part number
- Everything downstream depends on it.
- Material and specification
- Determines process route and validation.
- Annual volume and programme life
- The basis of the whole commercial case.
- PPAP level required
- Drives cost and timeline of onboarding.
- Tooling status
- New, transfer or customer-owned changes the project.
- SOP date
- Start of production is the fixed point everything works back from.
Questions suppliers ask
Should the IATF certificate number be published?
Yes, along with the certification body and the site it covers. Automotive buyers verify certification against the public IATF database as a matter of routine, and giving them the number is simply removing a step from a check they will perform anyway.
We supply the aftermarket, not OEMs. Does this still apply?
Partly. Aftermarket buyers care less about PPAP and more about fitment data, cross-references to OE part numbers, packaging and warranty. Publish the cross-reference table — it is the single most valuable page an aftermarket supplier can have.
How do we show capability without naming customers under NDA?
Describe the commodity, the process, the tolerance held, the annual volume and the segment, without the customer name. Sourcing engineers are assessing whether you have done work of that type at that level, and that can be established without breaching an agreement.
Check which documents and standards your buyer needs; requirements vary by market, customer and contract.
Plact Research. Plact's editorial desk for buyer-evidence research. Industry standards, documents and buyer questions are researched and drafted with Plact's AI tools, then reviewed by Praveen Kavuri before publication. Every claim cites the standard, regulation or public source it rests on.
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