FMEA Action Priority: AIAG-VDA AP tables vs the old RPN.
The 2019 AIAG-VDA FMEA Handbook quietly retired the Risk Priority Number. In its place is Action Priority (AP) — a High / Medium / Low ranking from a fixed lookup table. If your audits still chase RPN above 100, you are working to a superseded method. Here is what changed and how to apply AP.
From RPN to Action Priority
For decades, FMEA risk was ranked by the Risk Priority Number: RPN = Severity × Occurrence × Detection, each rated 1–10, giving 1–1000. Teams set a threshold (often 100 or 125) and actioned anything above it. The joint AIAG-VDA FMEA Handbook (1st edition, 2019) replaced RPN with Action Priority (AP), which classifies every failure mode as High, Medium or Low using a defined table of all 1,000 S/O/D combinations.
Why RPN was abandoned
- Different risks, same number. S=10, O=2, D=5 gives RPN 100. So does S=2, O=10, D=5. The first is a safety hazard you ship rarely; the second is a nuisance you ship constantly. RPN treats them as equal — they are not.
- Arbitrary thresholds. A cut-off of 100 means RPN 99 needs no action and 100 does, despite no real difference. Worse, a high-severity item with low O and D can score below the threshold and be ignored.
- Severity not weighted. Multiplication lets good detection mask a deadly failure. AP deliberately weights Severity first, then Occurrence, then Detection.
How Action Priority works
AP is not a calculation — it is a lookup. You still rate Severity, Occurrence and Detection 1–10 against the AIAG-VDA rating tables, then read the AP (High/Medium/Low) from the Action Priority table. The logic the table encodes:
| Severity | Occurrence | Detection | Typical AP |
|---|---|---|---|
| 9–10 (safety/regulatory) | any ≥ 2 | any | High |
| 9–10 | 1 | 2–10 | Medium |
| 7–8 | moderate–high | weak detection | High |
| 4–6 | moderate | moderate | Medium |
| 2–3 | low | strong | Low |
The priority hierarchy is explicit: Severity dominates, then Occurrence, then Detection. Two items can never share a priority just because their products match — the table looks at the actual S, O and D values.
What each level means for action:
- High: action is required. The team must identify improvement or formally justify and document why no further action is taken.
- Medium: action should be taken; justify if not.
- Low: action could be taken; no justification required.
Worked example
A pump shaft seal on an automotive water pump. Failure mode: seal leaks coolant.
| Rating | Value | Rationale |
|---|---|---|
| Severity | 8 | Coolant loss, engine overheat, vehicle disabled |
| Occurrence | 4 | Seen occasionally with current seal supplier |
| Detection | 6 | End-of-line leak test catches most, not all |
Old RPN: 8 × 4 × 6 = 192. Above a 100 threshold → "action," but the number tells you nothing about why.
New AP: with Severity 8 and moderate Occurrence and weak Detection, the AIAG-VDA table returns High. The team must act — improve the seal design or strengthen the leak test — and record the decision. AP also makes the driver obvious: detection (6) is the weakest link, so a better leak test is the first lever.
Transitioning from RPN to AP
If your control plans and customer forms still demand RPN, you do not have to choose — record both. Many Indian Tier-1 and Tier-2 suppliers run a transition period where the FMEA shows S, O, D, RPN and AP side by side. Steps:
- Re-rate S, O, D against the AIAG-VDA tables (the scales changed from the old AIAG 4th edition).
- Read AP from the Action Priority table.
- Sort and action by AP (High first), not by descending RPN.
- Document the rationale for every High and Medium where no action is taken.
Common mistakes
- Still ranking by RPN. Sorting the FMEA by RPN descending re-introduces every flaw AP was designed to remove.
- Reusing old rating scales. The AIAG-VDA S/O/D tables differ from the AIAG 4th edition; rating to the old scale gives the wrong AP.
- Skipping the rationale. AP requires documented justification when a High or Medium item is left without action — a frequent audit finding.
- Chasing the AP number, not the cause. AP sets priority; the value comes from fixing the dominant S, O or D driver.
For the cost case behind acting on high-risk failures, see cost of poor quality, and pull a ready FMEA worksheet from the templates library.
Frequently asked questions
Is RPN still used in FMEA?
The 2019 AIAG-VDA FMEA Handbook replaced RPN with Action Priority. Many customers still ask for RPN during the transition, so suppliers often report both, but AP is the current method for prioritising action.
What is Action Priority in FMEA?
Action Priority (AP) is a High / Medium / Low risk ranking read from a fixed AIAG-VDA table covering all combinations of Severity, Occurrence and Detection. It weights Severity first, then Occurrence, then Detection.
How is AP different from RPN?
RPN multiplies S, O and D into one number, so different risks can share a value and thresholds are arbitrary. AP looks up the actual S/O/D combination and prioritises Severity, avoiding the low-RPN trap for high-severity failures.
Do I need to recalculate my FMEA for AP?
Re-rate S, O and D against the AIAG-VDA tables (the scales changed), then read AP from the Action Priority table. You can keep RPN alongside it during a transition period.