The 5 Whys technique is a simple tool used to identify root causes of problems. It involves repeatedly asking "Why?" to get to the underlying cause. The document outlines: - How to use 5 Whys by defining the problem, then asking "Why?" with each response to reach the root cause in 3-5 iterations. - It can be used to analyze problems in quality improvement projects or in the field to better understand cause and effect. - An example demonstrates asking "Why?" five times to uncover the root cause of a machine stopping was a blocked oil filter, beyond the initial response of an overload trip.

1. ABB Basic Quality Tools Series
5 Whys
Basic technique for finding root causes
© ABB Group 9AKK105151D0113
15 July 2010, Slide 1

2. 5 Why’s - Content
What is it for?
• A quick and simple tool for understanding the real root causes of a
problem
• To push thinking about potential root causes to the root level.
Where could I use it?
• In the Q2 Analyze phase of an improvement project to understand
root causes.
• Where a quick tool is required for understanding cause and effect in
the field.
• Can be used in conjunction with a Fishbone diagram to understand
more “bones”.
How do I use it?
•
•
•
•
•
Establish the problem – write it down
Ask Why the problem is happening –write it down.
Ask Why again (to the last answer) and write it down.
Keep asking Why until the real root cause is identified.
This may take more or less than 5 Whys
Risks and how to avoid them
Example
© ABB Group 9AKK105151D0113
15 July 2010, Slide 2
Why?
.Why?
..Why? ..
.Why? ...
.Why?

3. 5 Why’s - What is it for?
Uses of this tool:
• As a simple tool that can be used at the problem location to challenge potential root causes .
• It can be used together with a Fishbone / Ishikawa diagram to establish more bones.
• It can be used in a team to thoroughly interrogate root causes.
Expected Benefits:
• By continually asking Why? The process encourages a more rigorous investigation of the real root
cause. It avoids the temptation to stick with the first answer given.
© ABB Group 9AKK105151D0113
15 July 2010, Slide 3

4. 5 Whys - Where could I use it?
Background:
Uses:
• Potential root causes require in depth
interrogation. Often the initial root causes
proposed are not the real root causes.
• Use it to identify root causes for problems which
are not clear and may have a deeper real cause.
• The 5 Why’s technique pushes and tests the
understanding of root causes and avoids
superficial causes being accepted.
© ABB Group 9AKK105151D0113
15 July 2010, Slide 4
• Use it during the analysis phase to gain a deeper
understanding of root cause by pushing
understanding of potential root causes.

5. 5 Whys - How do I use it?
Procedure and Guidance Notes:
•
Clarify the problem and write it down
It is important that there is clear understanding
of the problem before 5 Whys is started.
•
Ask Why the problem happens (Why 1)
Write down the potential cause
It can be good practice to use in conjunction
with a Fishbone diagram. Ask Why a each
“bone.”
State the problem
Ask Why the
problem happens
•
•
Ask Why the
problem happens
•
For the potential cause or outcome identified, ask why it happens
(Why 2)
Write down this next potential root cause.
•
For the next potential root cause or outcome, again ask why it
happens (Why 3)
Write down the new potential root cause
Repeat the process until the real root cause is identified.
•
Record the actual root cause identified.
•
Keep asking Why
Record
Root Cause
•
© ABB Group 9AKK105151D0113
15 July 2010, Slide 5
There is no magical formula about 5 Whys’
Sometimes you may get to the root cause after
two or three whys, sometimes you my have to
ask more than five times.
Stop when you have reached a root cause that
the team agree and can act on.

6. 5 Whys - Risks and how to avoid them:
Risks :
Steps to avoid them :
• Not asking Why enough times can lead to a superficial
root cause.
• Ensure that the process is repeated enough times until
the team is happy that a good potential root cause has
been identified.
© ABB Group 9AKK105151D0113
15 July 2010, Slide 6

7. 5 Whys - Example
1
Q : WHY has machine stopped ?
A : Overload tripped out
2
Q : WHY overload trip ?
A : Insufficient oil on shaft
4
Q : WHY is pump not efficient ?
A : Pump drive shaft worn
© ABB Group 9AKK105151D0113
15 July 2010, Slide 7
3
Q : WHY Insufficient oil ?
A : Oil pump is inefficient
5
Q : WHY is the pump shaft worn ?
A : Oil filter is blocked by metal scrap

8. 5 Whys - Example
1. Define the problem
Write down the problem being
investigated
Flashover during High Voltage Test on MV Transformer
1 Because the bushing socket was loose
2 Because the lock washer for the spring plate was not
installed properly
2. Identify potential root cause (Why 1)
Consider the potential root cause of the
problem ( can be done in conjunction
with a fishbone diagram)
3 Because the workman could not fit it in place and left it ou
– and did not tell anyone!
4 Because the spring plate was made too thick
3. Write down potential root cause
5 Because the subcontractor made a mistake when
transferring the dimensions from the drawing to the
CNC program
4. Identify potential root cause (Why 2)s
6 Because XXABB sent drawings, not CAD files to
subcontractors
Ask Why does the outcome (Why
1) occur? (why 2)

5. Write down potential root cause
Continue to ask Why does the previous
outcome occur until you’ve reached
potential root cause. Which you can record
6. Record the root cause
© ABB Group 9AKK105151D0113
15 July 2010, Slide 8
Sustain Solution: Send CAD files instead of drawings.
Change work procedure and meet with all sub-contractors
affected by change