PFMEA explained: seven steps, action priority and the control plan

A PFMEA, or process failure mode and effects analysis, is the structured review a manufacturing team carries out to find how a production or assembly process could fail to deliver the product characteristics the design needs, and to decide what to do about the risks before they reach a customer. In automotive supply chains, most PFMEAs now follow the AIAG and VDA FMEA Handbook, which replaced separate North American and German methods with a common seven-step approach.

This explainer covers what the handbook is and is not, the seven steps as they apply to a process, how action priority replaced the risk priority number, and how the analysis should connect to the control plan. It is aimed at quality engineers, manufacturing managers and supplier development teams in UK plants that ship to multinational vehicle makers.

The handbook behind the modern PFMEA

The VDA QMC webshop lists the AIAG and VDA FMEA Handbook as a first edition issued in June 2019, covering design FMEA, process FMEA and a supplemental FMEA for monitoring and system response. The listing says the handbook is aligned with SAE J1739, that Appendix F sets out the main changes from the AIAG fourth edition manual and VDA Volume 4, and that it does not define requirements: it explains steps, activities and tools. AIAG’s product page describes its current version as a second printing of the first edition that incorporates errata content and adds no new FMEA material.

That distinction matters in audits. The handbook describes a method; the obligation to use it comes from customer-specific requirements. AIAG’s page for its older fourth edition FMEA manual still advises users to check their customer’s requirements to confirm which methodology applies, so a supplier serving several vehicle makers may need to support more than one format. As of November 2026, AIAG’s FMEA overview page also carries a notice that a new FMEA publication is coming, without giving details, which is a reason to watch for a revised edition before rewriting internal procedures.

The seven PFMEA steps

AIAG’s errata for the first edition, version 2 dated 2 June 2020, confirms the step names used in the process chapter and corrects several process-specific details. Applied to a manufacturing process, the seven steps run as follows.

1. Planning and preparation. Define the scope, the team, the timing and the tools, and decide whether to start from a foundation or product family analysis.
2. Structure analysis. Break the process into a hierarchy of process item, process step and process work element, using the 4M categories of man, machine, material and environment to identify work elements.
3. Function analysis. Describe what each step and work element must achieve, phrased as an action verb followed by a noun, and link functions to product and process characteristics.
4. Failure analysis. Build the failure chain of effect, mode and cause across the structure, so that a cause at work element level is traced to its consequence for the next operation, the vehicle maker or the end user.
5. Risk analysis. Record current prevention and detection controls, rate severity, occurrence and detection, and assign an action priority.
6. Optimisation. Agree further actions, owners and target dates, then re-rate the risk once actions are complete.
7. Results documentation. Report the outcome, the actions taken and the remaining risk to management and, where required, the customer.

The structure step is where many process analyses improve most on older worksheets. Building the analysis around work elements forces the team to state which machine, fixture, operator task or material property could cause each failure, rather than listing generic causes such as operator error.

Action priority in place of RPN

Older FMEA worksheets multiplied the severity, occurrence and detection ratings into a risk priority number, or RPN; AIAG’s 2011 errata sheet for the fourth edition still shows RPN columns on the form. A common criticism, summarised in the Wikipedia entry on FMEA, is that the ratings are ordinal, so multiplying them can rank a less serious failure above a more serious one. The same entry records that the 2019 handbook replaced RPN with action priority.

Action priority, or AP, assigns each combination of ratings to a priority level using tables in the handbook. The 2020 errata narrowed the options in the process FMEA tables to high, medium and low, removing a not applicable option. It also corrected the handbook’s guidance so that where no action is taken, the risk is unchanged and the action priority is not reduced, and replaced the status “discarded” with “not implemented”, alongside “decision pending” and “implementation pending”.

The practical consequence is that a PFMEA team should stop setting numerical RPN thresholds in procedures and instead define how each priority level is handled, who can accept a medium or high item without action, and how that decision is recorded.

Linking the PFMEA to the control plan

The process analysis is only useful if its conclusions reach the shop floor. The prevention and detection controls recorded in risk analysis describe what the plant relies on to stop or catch each failure, and the control plan is where those checks are specified for production: what is measured, how, how often and what happens when a result is out of tolerance. AIAG’s Control Plan manual, first edition, published in March 2024, adds a safe launch phase and examples for highly automated manufacturing, and AIAG sells it alongside the FMEA handbook in its core tools bundles.

For example, a press line supplier that identifies incorrect die setting as a cause of a dimensional failure might record a set-up verification as a prevention control and a first-off measurement as a detection control. Both should then appear in the control plan with a frequency and reaction plan, and the same characteristic should be visible in the first-off release record. Our article on first-off inspection and production release covers that gate in more detail.

The link also runs backwards. When a defect escapes, the containment and root cause work should test whether the PFMEA recognised the cause and whether the rated controls actually worked, as discussed in our piece on defect containment and root cause. AIAG’s FMEA page describes the analysis as a before-the-event activity that should be completed before tooling and manufacturing equipment are developed and bought, but it remains a living document that should be revised after process changes and field problems.

Key points for quality and manufacturing teams

• Treat the AIAG and VDA handbook as a method reference and confirm each customer’s specific requirements for format and approval.
• Build the structure around process work elements using the 4M categories, not around generic causes.
• Replace RPN thresholds in procedures with rules for handling high, medium and low action priority.
• Record “no action” decisions explicitly; under the corrected handbook they do not reduce risk or priority.
• Carry every prevention and detection control into the control plan with a frequency and reaction plan.
• Update the PFMEA after engineering changes, process changes and escapes, and watch for a revised edition of the handbook.

Sources

• VDA QMC: AIAG and VDA FMEA Handbook (English), product listing
• AIAG: AIAG and VDA FMEA Handbook (FMEAAV-1)
• AIAG: AIAG and VDA FMEA Handbook errata, June 2020
• AIAG: Potential Failure Mode and Effects Analysis, fourth edition (FMEA-4)
• AIAG: FMEA fourth edition errata sheet, November 2011
• AIAG: Failure Mode and Effects Analysis overview
• AIAG: Control Plan manual (CP-1)
• Wikipedia: Failure mode and effects analysis

Sources checked in November 2026. Rules, rates and schemes can change after publication, so check the linked official pages before acting.