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Supplier 8D Discipline D0 to D8 Review Reference

A supplier 8D is only as good as its root cause and its escape analysis. This reference lists each discipline, what a supplier should provide, and the weak answers that should be sent back before you close a corrective action.

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Discipline	Name	What the supplier should provide	Reviewer question	Weak answer to send back
D0	Plan and emergency response	Confirmation the complaint was received and an owner assigned, with emergency actions to protect the customer	Who owns this and when was the first response sent?	No named owner or response beyond the acknowledgement date
D1	Form the team	Named team leader and members with the right functions	Is the process owner on the team?	Quality department only, no one from production or engineering
D2	Describe the problem	Who, what, where, when, how many, with part number, lot and defect description measured against the requirement	Is the defect described against the drawing requirement, with quantities?	Part was bad or a copy of the complaint text
D3	Interim containment action	Sorting of stock at the supplier, in transit and at the customer, with results and a way to identify certified parts	Where was stock checked and how are good parts marked?	Only the customer stock was sorted, or no results recorded
D3	Containment verification	Evidence that containment is effective, for example inspection records and sort counts	How many parts were sorted and how many rejected?	Statement that parts were checked with no counts
D4	Occurrence root cause	Verified cause of why the defect was made, found with a method such as 5 Whys, fishbone or is/is not analysis	How was the cause verified by turning it on and off?	Operator error or training with no process cause
D4	Escape root cause	Verified reason the defect was not detected at the supplier	Why did final inspection and the control plan not catch it?	Not addressed at all, only the making of the defect is analysed
D4	Systemic root cause	Management system gap behind the occurrence and escape, such as FMEA or change control	Which procedure or system allowed this?	Absent, so the same gap will reproduce the defect on other parts
D5	Choose permanent corrective actions	Actions that remove the root causes, with owners and dates	Does each action link to a verified cause?	Retrain operators, or increase inspection as the only action
D5	Verify before launch	Evidence the chosen action works before full implementation, such as a trial run	Was the action tested on a trial lot?	No evidence the action fixes the cause
D6	Implement and validate	Date of implementation, records of changed documents and new data showing the defect is gone	What data shows the fix is working?	Statement that the action is implemented with no data
D6	Remove interim containment	Defined criteria for ending containment and a decision record	On what evidence was containment stopped?	Containment dropped on a date with no criteria
D7	Prevent recurrence	Updated PFMEA, control plan, work instructions and checks across similar parts and lines	Which documents changed and which similar parts were checked?	Only the affected part number is covered
D7	Lessons learned	A record of what was learned and shared with other sites or products	Where is it recorded for reuse?	Blank or generic text
D8	Recognise the team and close	Customer agreement to close, with effectiveness monitoring plan	How long will you monitor and what is the trigger to reopen?	Closed by the supplier with no customer confirmation
D8	Effectiveness check	Follow-up data after a defined period, such as three months of ppm or no repeat lots	What was the defect rate in the months after closure?	No follow-up date set

The eight disciplines D1 to D8 are common practice and D0 was added in later versions of the method. Customers may use their own form. Use this as a review aid and follow your customer's supplier quality manual where it differs.

8D tracking in your ERP

Optional: see how open 8D requests could be linked to receiving rejections and supplier records.

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How to use this guide

Open the supplier's 8D report next to the table and search for the discipline you are reviewing, for example D4. Compare the report to the expected content, then use the reviewer question as your reply when the answer is thin. Export the table to Excel and add a column for accept or reject if you want a record of each review round. Many teams reject D4 and D7 most often, so spend your time there.

Search by discipline, such as D3 or D4
Use the reviewer question as written feedback
Look for escape and systemic causes, not only occurrence
Export the list for your review record

Why root cause is where reports fail

A strong D4 separates three questions: why the defect was made, why it was not detected, and why the system allowed it. Reports that stop at the first question tend to produce corrective actions that only retrain people. Ask the supplier to show how the cause was verified, for example by reproducing the defect when the cause is present and removing it when the cause is fixed. If a cause cannot be verified, it is still only a hypothesis.

Containment and closure

Containment in D3 should cover stock at the supplier, in transit, at your plant and at your customer if parts have shipped. Ask for sort counts and how certified parts are marked. At D8, do not close on the supplier's word. Agree an effectiveness window, commonly a few months or several lots, and reopen the case if the defect returns. Record the closure date and the evidence in your supplier file.

Common mistakes by the buyer

Buyers sometimes accept 8Ds that arrive on time but have no data, set response deadlines the supplier cannot meet with a real root cause, or close the case before containment is removed with criteria. Another mistake is not scoring the response quality. Track timeliness and quality of 8D responses on the supplier scorecard so poor reports show up in the next review.

Do not trade quality of analysis for speed alone
Ask for data at D3, D4 and D6
Track 8D quality on the scorecard
Reopen cases on repeat defects

Frequently Asked Questions

What is the difference between 8D and CAPA?

8D is a structured team problem-solving format, often used for customer and supplier complaints. CAPA is a broader quality system process that may use 8D, fishbone or other tools. An 8D can serve as the investigation record inside a CAPA.

Why is there a D0?

D0 was added to cover the planning step and emergency response before the team is formed. It records the trigger, who is responsible and the immediate actions to protect the customer. Some forms leave it out, which is acceptable if the content appears elsewhere.

How long should a supplier have to respond?

Many customers ask for containment within 24 hours, an initial root cause in a few days and the full report in around 30 days. Your supplier quality manual or agreement should state the actual times. Allow longer for complex failures.

Should every defect need an 8D?

No. Reserve 8D for significant, repeat or safety related failures. Minor one-off defects can be handled with a short corrective action request. Setting a threshold avoids filling the supplier's engineers with paperwork and protects the quality of the major reports.

If you receive many 8D reports by email, we can build an assistant that checks each one against these questions and links it to the receiving inspection history in your ERP.

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