5 Whys Root Cause Analysis Template
The 5 whys technique asks why repeatedly until the team reaches a cause it can fix. This template records the problem, the chain of answers, the evidence and the action, so the analysis survives beyond the meeting.
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5 Whys Root Cause Analysis Template
5 Whys Analysis RCA-2026-031
Company: Northfield Precision Ltd Date: 2026-10-20 Team: Production supervisor, setter, quality engineer, maintenance technician
Problem statement
On 18 October, 14 housings on order WO-45821 were found 0.15 mm undersize on bore diameter at final inspection.
Containment
Quarantined the order, 100 percent inspection of the remaining lot and the previous two lots.
The five whys
| Level | Answer | Evidence checked |
|---|---|---|
| Why 1 | The bore was cut undersize because the tool offset was wrong. | |
| Why 2 | The offset was wrong because it was set from a worn insert reading. | |
| Why 3 | The insert was not changed because the tool life counter was not reset after the last change. | |
| Why 4 | The counter was not reset because the step is not in the setup sheet. | |
| Why 5 | The setup sheet was not updated when the control was upgraded to the new software. |
Root cause
No process to revise setup sheets when the machine control or tooling method changes.
Corrective and preventive action
Add counter reset to the setup sheet, and add a revision check to the machine change procedure.
Owner and due date: Maintenance lead, 2026-11-06
Verification of effectiveness
Review tool life records and bore dimension data for the next ten lots.
Approvals
Each answer must be supported by evidence from the process, not opinion. Stop when you reach a cause the team can control. For complex or multiple causes use a fishbone or fault tree and consider a full 8D.
Find repeat causes across your ERP records
Optional review of how nonconformance and scrap history can reveal repeating root causes.
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How to use the template
State the problem with facts: what, where, when and how much. Record the containment action first so the customer is protected. Then ask why, answer from evidence, and ask why of that answer. Continue until the answer points to a missing or weak system, not a person. Typically that takes about five whys, but sometimes three or seven. Write the root cause, a corrective action, an owner, a due date and how you will verify that it worked.
- Go to the place and look at the evidence
- Do not accept human error as a final root cause
- Test the chain in reverse: therefore, therefore
Good and bad chains
A good chain is logical in both directions: if the root cause is fixed, the original problem cannot recur. A bad chain jumps to blaming an operator, stops at a symptom, or follows only one of several possible branches. If the answer to a why has two causes, split the analysis and follow each branch. The example in the form walks from an undersize bore through a stale tool offset to a missing process for updating setup sheets.
When to use something else
The 5 whys is quick and good for simple or moderately complex problems. For problems with many possible causes, use a fishbone diagram first, then test the likely causes. For customer complaints that need a formal response, use an 8D or the format your customer requires. Record the result in your CAPA or nonconformance system so it can be tracked and trended.
Frequently Asked Questions
Do I always need exactly five whys?
No. Five is a rule of thumb from the Toyota Production System. Stop when you reach a cause that, if removed, prevents the problem and that your team can control. It might take three whys or eight.
What is the weakness of the 5 whys method?
It can oversimplify problems with several causes, depends on the team's knowledge and may stop too early. Support each answer with evidence and use other tools such as fishbone or fault tree analysis for complex problems.
How is it different from an 8D?
The 5 whys is one technique for finding root cause. An 8D is a full problem-solving process with a team, containment, root cause, corrective action, verification and prevention. The 5 whys often sits inside step four of an 8D.
Who should be in the room?
People who know the process: the operator, the supervisor, quality, maintenance and engineering as needed. A facilitator who asks questions and keeps the team on evidence helps. Avoid a room of managers only.
Netray can help link root cause records to the ERP orders, lots and suppliers affected so you can see repeat causes across the plant.
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