D6 is where the corrective action from D5 has to prove itself. A D6 that says “implemented” or “verified OK” tells the customer the action happened, not that it worked. This page covers what evidence belongs in D6, with examples from automotive, aerospace, electronics, and food. It also fits medical devices and general manufacturing. Your customer’s format and closure rules come first.
Implemented is not effective
A D6 usually needs to answer two questions. Is the action in place, everywhere it should be? And does it remove the cause, shown by data from after the change? Containment results don’t count here; they show you protected the customer, not that the cause is gone. See 8D corrective action vs containment.
Evidence that usually belongs in D6
- Before-and-after data for the characteristic that failed, with lot numbers or dates.
- A test showing the action handles the cause, such as a challenge with known-bad parts.
- Records that the new method is in use: revised document, setting, or system screen.
- A monitoring period or volume, stated up front, and its results.
- Removal of temporary containment once the data supports it, with the date.
- For detection actions, proof the check now catches the defect.
Weak vs evidenced D6: examples from four sectors
The examples below are illustrative and fictional, not from real cases.
Automotive, machining (illustrative)
Weak D6: “Implemented new tool change interval. Verified OK.”
Verification evidence: Bore diameter capability before and after the change, measured on consecutive production lots, with the lot numbers listed.
Effectiveness over time: No repeat of the bore defect at the customer over an agreed period, with incoming results confirmed.
Aerospace, composites (illustrative)
Weak D6: “Operators trained on new cure procedure.”
Verification evidence: Cure records from the revised procedure for the following parts, plus ultrasonic inspection results of those parts.
Effectiveness over time: First articles and later parts inspected without the porosity finding.
Electronics, test (illustrative)
Weak D6: “Test program updated.”
Verification evidence: The updated program run against known-bad sample boards to show it now catches the defect, then production yield data.
Effectiveness over time: Field returns for the failure mode tracked for the agreed period with no repeat.
Food, foreign body (illustrative)
Weak D6: “Sieve replaced.”
Verification evidence: Detection challenge with test pieces after the change, and the new inspection checks recorded each shift.
Effectiveness over time: Complaint data for the product reviewed after the agreed period, with no repeat.
Written your D6? Get a free Accept / Conditional / Reject advisory on the report text, with missing evidence named, before it goes to the customer.
8D Gate is a free pre-send readiness advisory. It doesn't replace the customer's decision. We don't store your 8D body in our database; you can delete anytime. Anthropic processes the text for the review.
When results aren’t in yet
Customers often want the 8D before the monitoring period ends. Say what is done and what is open: the verification so far, the planned check, the date, and who owns it. A D6 with a clear open item is easier to accept than one that claims closure without data.
Link D6 back to D4
D6 can only show effectiveness against the cause you proved in D4. If D4 is weak, D6 has nothing to measure. See weak D4 root cause examples and how to write D4 root cause.
Before you send
- D6 shows data from after the change, not only the change itself.
- The monitoring period or volume is stated, with results or a date.
- The evidence matches the D4 cause, for both occurrence and escape.
- Containment status and removal date are stated.
- Any open item has an owner and a due date.
Use the 8D report template for the structure, and the 8D containment actions examples for D3. If a report came back, see 8D rejected? What to do next.
FAQ
- What is the difference between verification and validation in D6?
- Terms vary by customer. Often verification means proving the action was put in place and works on the process, and validation means showing over time that the problem doesn’t come back. Use your customer’s definitions where they give them.
- How long should we monitor before closing?
- Follow the customer’s requirement. If none is given, pick a period or volume that would have shown the defect at its original rate, and state it in the report.
- Does 8D Gate verify our results?
- No. It is a pre-send readiness check of the report text: it flags D6 sections without evidence and asks questions. It doesn’t see your data and isn’t a customer decision. The review tool is v0.1: it reviews English 8D reports, and the interface and report are in English. Templates are also available in German, Czech and Polish.
Free pre-send readiness check
Before the report goes out, run the text through the free supplier 8D readiness check.
Paste text or upload PDF, DOCX, or Excel. You get an Accept / Conditional / Reject advisory, a score, section ratings, missing evidence, and questions to close gaps, with a PDF download. It is a pre-send readiness check for your team, not a customer decision.
8D Gate is a free pre-send readiness advisory. It doesn't replace the customer's decision. We don't store your 8D body in our database; you can delete anytime. Anthropic processes the text for the review.
Get the free 8D / D4 checklist
Keep the one-page version next to your D6. It covers D1–D8 and goes deeper on D4 occurrence, escape, and verification.
Get the free 8D / D4 checklist