Supplier Corrective Action Process: End-to-End

The supplier corrective action process mirrors the internal corrective action process, with the work performed by the supplier and the verification performed by the customer. The instrument is the SCAR; the format is usually 8D-aligned.

What sits inside the process

• Trigger detection (incoming inspection, in-process find, escape to customer, audit, PPAP/FAI failure).
• SCAR issue with severity, response dates, and evidence.
• Supplier 8D response in stages.
• Customer evaluation at each stage with accept or reject decisions.
• Escalation when stages slip or responses fail.
• Effectiveness verification and closure with read-across.

Triggers worth a SCAR

• Same failure mode on two or more lots within a defined window.
• Single defect on a safety- or function-critical characteristic.
• Any escape that reaches the end customer.
• Audit nonconformance (system, process, or product).
• Failed PPAP or FAI element the supplier did not self-identify.
• PPM threshold breach in the scorecard.

Single isolated defects with no pattern usually do not justify a SCAR. Use a documented screening rule so SCAR issuance is consistent across the SQE team. See the broader SCAR overview.

Issuing the SCAR

A SCAR ready to issue contains the problem statement, severity classification, affected lots and serial numbers, evidence (photos, measurements, returned samples), the source NCR, the required response dates for each stage, and the format the response is expected in. Issuing a SCAR with missing fields invites a weak response — the supplier copies the gaps back.

Supplier response stages

1. D1-D2 (8 hours): team formed, problem statement re-stated.
2. D3 (24-48 hours): interim containment with defined scope at supplier, customer, and sub-tier.
3. D4 (14 days): root cause analysis with occurrence and detection causes stated separately.
4. D5 (30 days): permanent corrective action plan with action rows, owners, dates, evidence.
5. D6 (per plan): implementation evidence attached.
6. D7 (closure): prevent-recurrence and read-across.
7. D8: team close-out and acknowledgment.
8. Effectiveness: 60-90 days after implementation.

Evaluating each stage

Reject and reissue if any of the following are true at the relevant stage:

• D3 containment scope is undefined or does not appear to cover all suspect inventory.
• D4 root cause is a restated symptom ("operator error," "out of spec").
• D4 has only occurrence or only detection cause, not both.
• D5 plan is entirely training and procedure updates with no engineering control.
• D5 owners are departments rather than named individuals.
• Effectiveness criteria are vague or missing acceptance thresholds.
• D7 read-across is missing or claimed without evidence.

First-pass acceptance rate is a leading indicator of supplier capability. Accepting weak responses to keep the SCAR moving teaches the supplier that the bar is lower than the format implies — and the next response will be weaker.

Escalation

• Level 1 — standard SCAR managed by the SQE; aging at 75% of stage SLA triggers an automatic reminder.
• Level 2 — repeat SCAR, missed stage, or two consecutive rejected responses; triggers a managed quality plan, on-site visit, and 100% incoming at the customer.
• Level 3 — controlled shipping (e.g. automotive CS-1: supplier sorts 100% with second-side independent verification before release), business hold, re-sourcing plan opened.

Escalation thresholds should be in the supplier quality agreement, not invented when the SCAR is failing. See the scorecard template for how escalation feeds tiering.

Effectiveness verification

At 60-90 days the SCAR enters effectiveness verification. Criteria written when the D5 plan was approved: zero recurrence over a defined lot count, zero customer complaints related to the failure mode, the new control function rate at 100%. See the dedicated effectiveness verification guide for data sources and pitfalls.

Closure and read-across

Close with effectiveness evidence attached and read-across documented — every other part the supplier ships to the customer that uses the same process, the same tooling, or the same sub-tier. The closed SCAR feeds the supplier scorecard's SCAR response time and quality metrics for the closing quarter.

Examples

Aerospace machining — Level 1 SCAR closed on first submission

Bent locating pin on a turbine bracket. SCAR issued at major severity. Supplier acknowledged in 6 hours, containment in 30 hours (full lot sort plus WIP), root cause identified within 9 days (incorrect fixture rev), corrective action plan in 22 days (fixture rev control gate plus operator-verified setup sheet), effectiveness verified at 75 days across 6 production runs. First-pass acceptance; supplier remained Tier A.

Automotive injection molder — Level 2 SCAR with rejection cycles

Short-shot defect on an interior part. First D4 response cited "operator inattention" — rejected. Second D4 cited "machine pressure setting" — accepted with note that detection cause was still missing. Final D5 added in-cycle pressure monitoring (occurrence) and end-of-line vision check (detection). Escalation to Level 2 triggered by the two D4 rejections; on-site visit performed. Effectiveness verified at 90 days; supplier moved from Tier C toward Tier B over two quarters.

FAQ

How long does a supplier corrective action take?

Standard automotive 8D timeline: 8 hours to acknowledge, 24-48 hours to containment, 14 days to root cause, 30 days to plan, 60-90 days to effectiveness verified.

What triggers a SCAR?

Repeat defects, single defects on safety- or function-critical characteristics, any escape to the end customer, audit nonconformances, failed PPAP/FAI items, or PPM threshold breaches.

Who owns the supplier corrective action?

The supplier owns the investigation, containment, and execution. The customer's SQE owns the SCAR, the acceptance decision at each stage, and the effectiveness verification.

How does the supplier corrective action process connect to CAPA?

The customer's CAPA record holds the full audit trail: source NCR, issued SCAR, supplier response, customer verification, effectiveness data. The SCAR is the supplier-facing instrument; CAPA is the customer's record of the loop. See CAPA process.