FMEA Step by Step: A CQE Guide to Failure Mode and Effects Analysis
FMEA is the quality engineer’s primary tool for anticipating failures before they happen. Here is how to build one and how it is tested on the CQE.
The best time to catch a failure is before it happens. Failure Mode and Effects Analysis (FMEA) is the structured method quality engineers use to do exactly that—systematically anticipating how a product or process could fail and prioritizing action before customers are affected. It sits squarely in the risk management portion of the CQE Body of Knowledge.
I am John Lee of Alpha Training and Consulting. Here is how to build an FMEA step by step, along with the concepts the exam tests most often.
Design FMEA vs. process FMEA
FMEAs come in two primary forms. A design FMEA examines how a product could fail to meet its requirements—weaknesses in the design itself. A process FMEA examines how the manufacturing or assembly process could introduce defects. The methodology is identical; only the scope differs.
The step-by-step process
- 1Define the scope: the system, subsystem, or process step under analysis.
- 2List functions and requirements for each element.
- 3Identify potential failure modes—the ways each element could fail to perform its function.
- 4Determine the effects of each failure and rate their Severity (1 to 10).
- 5Identify potential causes and rate their Occurrence, or likelihood (1 to 10).
- 6Describe current controls and rate Detection—the ability to catch the failure before it escapes (1 to 10).
- 7Calculate the Risk Priority Number and identify the highest-priority risks.
- 8Define and implement actions to reduce risk, then re-score to confirm improvement.
Understanding severity, occurrence, and detection
| Factor | Question it answers | High score means |
|---|---|---|
| Severity | How bad is the effect if the failure occurs? | A serious or dangerous consequence |
| Occurrence | How likely is the cause to happen? | The failure is expected frequently |
| Detection | How likely are we to catch it first? | Current controls are poor at detecting it |
Using the RPN wisely
The Risk Priority Number—Severity times Occurrence times Detection—gives a single figure to rank risks. But treat it as a guide, not a verdict. A failure with a severity of 10 deserves attention even if its RPN is modest, because the consequence is catastrophic. The current AIAG-VDA approach uses an action priority table precisely to keep severity from being diluted by the multiplication.
FMEA does not stand alone. It feeds control plans, drives design reviews, and connects directly to root cause analysis when a failure does occur. Study it alongside our guides to root cause analysis and reliability to see how these tools reinforce one another.
Frequently asked questions
What is the difference between a design FMEA and a process FMEA?+
A design FMEA (DFMEA) analyzes potential failures in a product’s design, focusing on function and requirements. A process FMEA (PFMEA) analyzes potential failures in the manufacturing or assembly process. Both use the same severity, occurrence, and detection logic.
How is the Risk Priority Number calculated?+
RPN equals Severity multiplied by Occurrence multiplied by Detection. Each factor is typically scored from 1 to 10, so RPN ranges from 1 to 1000. Higher RPNs indicate higher-priority risks.
Should you always act on the highest RPN first?+
Not blindly. High severity should draw attention regardless of RPN—a catastrophic failure that is rare and detectable can still be unacceptable. Modern practice supplements RPN with severity-based action priority.
Written by
John Lee
President, Alpha Training and Consulting
John Lee has more than 25 years of experience in quality engineering and has personally earned every ASQ certification, including the Certified Quality Engineer (CQE). A Shingo Award–winning author, he has helped thousands of engineers pass their ASQ exams on the first attempt with a 94% first-time pass rate.
Certifications: BSME, MBA, CMQ/OE, CQE, CRE, CQA, CQIA, CQI, CCT, CQPA, CQT, CHA, CBA, CSQE, CSQP, CCQM, CSSYB, CSSGB, CSSBB, CPGP, CMBB
Alpha Training and Consulting is an independent training provider and is not affiliated with, endorsed by, or sponsored by ASQ. "ASQ" and "Certified Quality Engineer (CQE)" are trademarks of the American Society for Quality. Exam policies, fees, and Body of Knowledge weightings are set by ASQ and can change—always confirm current details at asq.org.