What Is D6 (Implement & Validate Corrective Action) in the 8D Process? #
Till D5 you are doing planning and analysis, the actual action starts from D6 step. This step focus on Implement and Validate Corrective Action and then verifying their effectiveness through data, inspection, or process results.
“A corrective action is not real until it’s implemented, measured, and prove effective.”
In short, D6 is about implementing it and prove to effectiveness.
Therefore, the Objective of D6 step is to:
- Implement all approved corrective actions.
- Verify their effectiveness with evidence (SPC, inspection data, trials).
- Ensure the defect no more occurs under normal production conditions.
- Remove containment, after validation of Corrective Action.
- Document verification results in the 8D report.
How to Implement and Validate Corrective Action (Explained) #
Let’s understand how you can perform D6 step execution with example.
Step 1 – Implement Each Corrective Action
From D5 we have:
| Type | Corrective Action Planned | Responsibility | Target Date |
| Occurrence Cause | Replace faulty gas regulator; include regulator O-ring inspection in PM checklist; install gas-flow indicator | Maintenance Engineer – Kiran Deshmukh | 20 Oct 2025 |
| Non-Detection Cause | Replace non-functional inspection lamp; add two LED lights (800 Lux min); create PM checklist for lighting; retrain inspectors | QA Engineer – Rahul Patil | 21 Oct 2025 |
Example Implementation Record
- Gas regulator replaced on 20 Oct 2025.
- Flow indicator installed and calibrated.
- New PM checklist (Ref: PM-WELD-021) released and signed.
- Lighting upgraded to 900 Lux; illumination audit performed.
- Training conducted 21 Oct 2025 for all QA inspectors.
Step 2 – Validate Effectiveness of Actions
Validation must be based on data, not based on opinion. Use measurable evidence to show the defect is eliminate.
Methods for Effectiveness Validation
| Method | What to Check | Example for Weld Defect |
| Trial Production Run | Produce a defined batch after correction | 500 pcs run on Welding Line 2 – 0 defects found |
| SPC Chart | Check process stability over time | Gas flow recorded stable 10 ± 0.3 LPM |
| Inspection Data | Verify visual and dimensional checks | 100% OK in 3 lots post-action |
| PPM Trend | Monitor reject rate post-implementation | Dropped from 20 000 PPM → 0 PPM |
| Customer Feedback | Confirm no new complaints | Customer confirmed no further issues as of 25 Oct 2025 |
✅ Result: Actions effective: No failure observed in subsequent lots.
Step 3 – Document Evidence in Template
In 8D format “Effectiveness and Evidence of Verification” fields should be fill as follows:
| Sr No. | Corrective Action | Completed On | Effectiveness | Evidence of Verification |
| 1 | Replaced gas regulator & added flow indicator; PM checklist released | 20 Oct 2025 | No weld spatter in 3 production lots | SPC chart, PM record, photo proof attached |
| 2 | Lighting upgraded & inspection PM checklist added | 21 Oct 2025 | All weak welds visually detected in trial batch | Lux audit report, training attendance sheet |
Attach supporting documents (e.g., photos, checklists, SPC charts) as PDF appendices.
Step 4 – Remove Containment (after Validation Success)
Once data shows there is no defects, communicate to management and customer that we can remove containment action now. Because we already implemented and verify the effectiveness of corrective action and it is effective.
Example note for 8D closure:
“After three validated production lots (2 000 pcs) with zero defects, containment inspection was stopped on 24 Oct 2025. Customer approval received 25 Oct 2025.”
This marks the transition from temporary problem fix to stable process.
Tools Used in D6 step (Implement and Validate Corrective Action)
| Tool | Purpose |
| SPC (Statistical Process Control) | Monitor stability of key parameters like gas flow. |
| Control Charts (X̄ – R) | Validate process mean and range within control limits. |
| Check Sheets / Inspection Logs | Record results of trial runs. |
| Before–After Pareto | Show defect reduction quantitatively. |
| Photographic Evidence | Provide visual proof of changes. |
Step 5 – Communicate Results
After successful validation:
- Update the status in management review and to customer.
- Present before–after data (PPM trend chart).
- Retain records for audit traceability (IATF 16949 – Clause 10.2.5).
Customer Communication Example
“All corrective actions implemented and validated. Post-implementation SPC data and visual inspection confirm zero defects for three consecutive lots. Containment lifted on 24 Oct 2025 with customer concurrence.”
Key Indicators of Effective D6 step #
| Indicator | Target |
| Defect Recurrence | Zero in at least three lots |
| Process Stability (Cp/Cpk) | ≥ 1.33 after action |
| Customer Feedback | No complaint reopened |
| SPC Trend | Within UCL/LCL for all key parameters |
If these are met, you can proceed to D7.
How D6 Links to next steps
Once you implement and verify corrective action, the next steps are to prevent recurrence:
- D6 – D7 (Prevent Recurrence) = These actions must be standardized and updated in other documents to prevent recurrence.
- D7 – Audit / customer review = Provides evidence of effectiveness for 8D closure approval.
Summary of D6 step #
- D6 proves that corrective actions are working under real production.
- Verification must be based on data (SPC, inspection, customer feedback).
- Always record implementation date, effectiveness, and evidence in the template.
- Containment is removed after this step.
- Effective D6 ensures a stable, repeatable, defect-free process.
“If you can’t prove it with data, the problem is not yet solved.”
