5 Whys: What it is and how to apply the method to solve root problems

Have you ever faced a recurring problem and thought, “Why does this keep happening?”

The 5 Whys methodology helps you get to the root of the issue — in a simple, direct, and effective way by asking just one question: why?

What is the 5 Whys method?

When faced with a problem, it is common to try to solve it by looking at its symptoms. It is something that comes from human instinct. However, this type of approach has a partial or temporary effect. In addition, without treating its root cause, the problem may recur – which is known as recidivism.

To deal with this, Taiichi Ohno, Toyota engineer, created the methodology in the 70s, detailed in his book Toyota System Production (TPS). In addition to the 5 Whys, Taiichi also invented lean thinking and kanban.

In his approach, Taiichi created a way to solve internal problems efficiently and simply. These characteristics have made the 5 Whys so popular. That’s why many people still believe that this is a tool that is unique to the automotive industry.

However, this strategy works in companies of any size or segment.

The important thing is that there is a need to solve problems and implement corrective actions quickly and easily.

How to apply the 5 whys?

The application of the 5 whys is quite simple: when you identify a problem, you ask yourself “why” five times, until you get to the cause of the problem. It is important to clarify that “five” is just a number suggested by the method.

There will be cases where it will be necessary to continue beyond the five questions, just as there will also be situations where the root cause of the problem will emerge before the fifth why.

What’s the step-by-step to use the 5 Whys?

Build a qualified team: One person cannot solve everything. Count on a team that knows the process and the details of the problem that needs to be corrected well. It should have a facilitator, who will guide the other participants and help to keep the focus on identifying the causes of the subject analyzed.
Clearly describe the problem: To do this, use documents, records, emails and other useful items, observing everything that is happening. Thus, everyone will have the same focus, and details will not go unnoticed.
Ask: “Why did this problem occur?”: Avoid answering this question with assumptions or hypotheses. Make sure that each answer is based on concrete evidence and based on facts or data.
Keep asking “why” until you reach the root cause: Remember that five is just a reference. In certain problems you will need to repeat the question more times, while in others you will be able to determine the root cause before that.
Define corrective actions, assign responsibilities, and monitor results: Another point that usually causes confusion is knowing the correct time to close the questions and finish the analysis. This usually occurs when the question is asked and an answer is not reached with evidence.

Once the root cause of the problem has been identified, the team must define what actions will be taken to correct it, preventing it from recurring.

What’s a clear example of using the 5 Whys?

You already know the concept behind the operation of the 5 Whys. To help you put this into practice, we have prepared an illustrative example of the application of this tool.

Example of applying the 5 Whys:

Problem that needs to be analyzed: Parts are incompletely painted.

Why 1: The paint booth was turned off in the middle of the process.
Why 2: There was a lack of electricity.
Why 3: The circuit breaker ended up tripping.
Why 4: The circuit breaker wiring melted and it shorted.
Why 5: The cabling installed in the circuit breaker was inadequate and of poor quality.

That’s the root cause!

How to validate using reverse logic? Think of it this way:

The power cabling was inadequate;
This caused overheating;
Overheating caused the plastic cover to melt and short;
The short circuit tripped the circuit breaker and interrupted the operation of the cabin;
This meant that the painting process was not completed.

What to do after identifying the root cause?

With the identification of the root cause, the team must discuss and define what actions will be implemented to prevent the problem from reoccurring. Following our example above, an appropriate measure would be to replace the power cabling with one that meets the paint booth manufacturer’s recommendations.

The team responsible for maintaining the equipment should monitor the implementation of these corrective actions and assess whether they were effective and actually eliminated the cause of the problem.

What if the problem persists?

If the root cause persists even after analyzing and implementing corrective measures, repeat the 5 Whys method. This persistence is an indicator that the real reason for the problem has not yet been identified and solved correctly – and that this needs to be done.

What’s the best way to use the 5 Whys?

In addition to understanding the process of applying the 5 whys, it is also necessary to follow good practices to ensure that the methodology is used in the best way.

Describe the problem clearly

First of all, gather the team responsible for identifying the cause of the problem and describe it as accurately as possible. Be as objective and concise as possible to increase the clarity, efficiency, and simplicity of the process.

Document the entire process carefully

As you have already seen, recording the steps and writing down the decisions and tasks is essential. This prevents failures, brings transparency and streamlines the entire process. This also optimizes communication for everyone involved — especially when done through quality management software.

Plan the solutions and implement them correctly

Don’t forget: finding the cause of a problem is not enough, it is essential to define solutions for it. Together with the entire team, understand what will correct the issue and prevent it from recurring. Also, record all this and define those responsible for each action.

The 5W2H methodology and action plan templates can be great allies to facilitate this entire process.

Create ways to monitor results and review the measures adopted

A company’s processes and activities are constantly changing. Likewise, any problems (and their root causes) can also change. Therefore, create ways to measure the efficiency of the solutions adopted and review all this whenever an element linked to it is changed.

Know when to stop

Finally, something that may seem simple, but is very important: know when to stop. Complex activities have several elements that are connected. Thus, a problem that seemed simple at first may actually be the symptom of something deeper.

Therefore, stay focused and always try to understand what, objectively, is causing that situation — and what may actually be a new problem.

In conclusion: Why use the 5 Whys?

The 5 Whys methodology is a simple, low-cost, and highly effective tool for companies that want to solve problems in a structured way — addressing the cause, not just the symptoms.

By combining a qualified team that knows the method and its clear and organized processes, you have a powerful tool for identifying and resolving failures.