Overview
Action Priority serves as a risk-based prioritization mechanism that bridges FMEA risk assessment and corrective action management. Unlike traditional Risk Priority Numbers (RPN), which multiply severity, occurrence, and detection into a single score, TestAuto2 implements a threshold-based approach aligned with AIAG-VDA FMEA methodology. Action Priority values are determined from pre-mitigation or post-mitigation Severity, Occurrence, and Detection ratings, then used to track and manage mitigation tasks.
Action Priority is NOT automatically inherited from RPN. Instead, it is calculated using logic-based thresholds that consider the individual S/O/D components. This allows organizations to apply judgment beyond simple numerical scoring and align prioritization with their risk tolerance and safety standards.
Enumeration Values
| Value | Label | Color Code | Sort Order | Visual Icon | Description |
|---|
H | High | #DC143C (Crimson) | 0 | 🔴 | Highest priority — corrective action is required immediately to improve prevention and/or detection controls. Indicates high residual risk or high pre-mitigation risk that poses significant threat to product safety or customer satisfaction. |
M | Medium | #FF8C00 (Dark Orange) | 1 | 🟠 | Medium priority — corrective action should be taken during the current project phase to improve controls. Indicates moderate residual risk that should be addressed within planned timelines. |
L | Low | #4CAF50 (Medium Green) | 2 | 🟢 | Low priority — corrective action is optional or deferred. Indicates acceptable residual risk where controls are currently adequate, though improvements could be considered in future releases or during continuous improvement cycles. |
Determination Logic
Action Priority is calculated using threshold-based decision logic rather than RPN multiplication. The following decision tree shows how pre-mitigation AP is determined from Severity, Occurrence, and Detection:
IF Severity >= 9
THEN AP = H
ELSE IF (Severity >= 5 AND Occurrence >= 4)
THEN AP = H
ELSE IF (Severity >= 6 AND Occurrence >= 4 AND Detection >= 5)
THEN AP = H
ELSE IF (Severity >= 6 OR Occurrence >= 7 OR Detection >= 8)
THEN AP = M
ELSE IF (Severity >= 5 OR Occurrence >= 5 OR Detection >= 6)
THEN AP = M
ELSE
THEN AP = L
- Original Severity (unchanged, as severity is inherent to the failure mode effect)
- Updated Occurrence (post-mitigation rating reflecting prevention controls)
- Updated Detection (post-mitigation rating reflecting detection controls)
Severity represents the seriousness of the failure mode effect — it is an inherent property of what happens if the failure occurs. Risk controls can prevent the failure (occurrence) or detect it before harm (detection), but they cannot change what the effect would be. Therefore, severity never changes between pre- and post-mitigation assessments.
Action Priority Assignment Workflow
Step 1: Identify Failure Mode
Enter the failure mode description in the FMEA risksheet. Link the failure mode to the relevant system element, function, or design component.
Step 2: Rate Severity (1–10)
Assign a severity rating based on the consequences if the failure mode occurs, using automotive safety standards:
- 9–10: Hazardous without warning; safety-critical; severe injury or fatality risk
- 7–8: Major effect; significant customer dissatisfaction; operational failure
- 5–6: Moderate effect; affects usability or convenience
- 1–4: Minor effect; cosmetic or negligible customer impact
Step 3: Rate Occurrence (0–10)
Assign an occurrence rating reflecting the probability that the failure mode will occur before mitigation controls are implemented:
- 0: Unrated (default; do not leave blank in production analysis)
- 7–10: Likely to occur; frequent or probable
- 4–6: Occasional; possible under certain conditions
- 1–3: Remote; unlikely under normal use
Step 4: Rate Detection (0–10)
Assign a detection rating reflecting the effectiveness of current controls at detecting the failure mode before it reaches the customer:
- 0: Unrated (default)
- 1–3: High detection effectiveness; error-proof design or automated gauging
- 4–6: Moderate detection; manual inspection with reasonable confidence
- 7–10: Low detection effectiveness; no controls or only visual inspection
Step 5: Calculate Pre-mitigation Action Priority
The risksheet formula automatically calculates AP using the threshold logic above. Verify the result and review with the team.
Step 6: Define Risk Controls
Identify and document prevention controls (reduce occurrence) and detection controls (improve detection capability). Assign risk control work items to team members.
Step 7: Update Post-mitigation Ratings
After controls are implemented or validated, update the post-mitigation Occurrence and post-mitigation Detection ratings. The risksheet recalculates post-mitigation AP automatically.
Step 8: Track Residual Risk
Compare pre-mitigation AP to post-mitigation AP. Verify that high-priority items have been reduced to medium or low priority. If residual AP remains high, escalate and plan additional controls.
Visual Encoding and Traffic Light System
TestAuto2 applies a three-color traffic light scheme to Action Priority for immediate visual risk assessment:
Cell Decorator Behavior:
- Risksheet cells display the AP label (H/M/L) in large text with the full label below in smaller font
- Row headers in FMEA hierarchies are colored to reflect post-mitigation AP, signaling final residual risk
- Column sorting by AP automatically places high-priority items first (sort order: H=0, M=1, L=2), supporting risk-based workflow sequencing
Relationship to RPN and Risk Priority Number
Traditional FMEA approaches use Risk Priority Number (RPN) = Severity × Occurrence × Detection to rank failure modes on a continuous 1–1000 scale. TestAuto2’s threshold-based Action Priority offers advantages:
| Aspect | RPN (Multiplicative) | Action Priority (Threshold-Based) |
|---|
| Sensitivity | Overly sensitive to small changes; can hide high-severity hazards | Accounts for severity dominance; S=9 always triggers H regardless of O/D |
| Organizational Variability | Requires calibration of RPN thresholds (e.g., RPN > 50 = action required) | Clear, industry-standard thresholds aligned with AIAG-VDA FMEA-4 |
| Interpretation | Relative ranking only; no absolute risk meaning | Tied to risk acceptance criteria and safety standards |
| Adaptability | Single threshold fits all products and contexts | Thresholds can be tuned per organization or product family |
Some organizations calculate and display RPN values for historical comparison, then use Action Priority thresholds for actual corrective action decisions. This hybrid approach is supported in TestAuto2 through custom formula columns.
Action Priority in FMEA Workflow Views
The FMEA risksheet in TestAuto2 includes progressive workflow views that guide users through structured analysis. Action Priority appears in specific views:
- View 2: Initial Risk Ranking — Displays pre-mitigation AP to identify priority failure modes upfront
- View 4: Define Mitigations — Shows both pre- and post-mitigation AP side-by-side to compare risk reduction
- View 6: Final Risk Evaluation — Highlights post-mitigation AP to confirm residual risk is acceptable
- View 7: Risk Summary — Summarizes count of H/M/L items and status of corrective actions
Action Priority and Mitigation Task Management
Action Priority directly influences corrective action tracking and task creation:
| Priority | Task Creation Mandate | Tracking Requirements | Timeline Urgency |
|---|
| H | Mandatory formal task | Assigned owner, due date, approval gate | Immediate or current phase |
| M | Recommended; may be consolidated into phase tasks | Assigned owner, target completion | Current or next phase |
| L | Optional; informational only; may be reviewed in continuous improvement cycle | Optional tracking; may group into backlog | Deferred or future release |
- Each failure mode with AP = H must have a linked risk control (riskControl work item)
- Risk controls are tracked separately with assignee, status (draft/approved/verified), and evidence links
- Failure Mode AP provides the rationale; Risk Control status provides the execution tracking
Use Action Priority as input to phase planning. Organize mitigation efforts into phases: Phase 1 addresses all H items; Phase 2 addresses M items; Phase 3 reviews L items. This phased approach aligns FMEA analysis with realistic project constraints while maintaining safety focus.
System FMEA (SFMEA) vs. Design FMEA (DFMEA) vs. Process FMEA (PFMEA)
Action Priority applies consistently across all three FMEA levels in TestAuto2:
| Level | Scope | Typical AP Determination | Residual Risk Target |
|---|
| SFMEA (System) | System-level functions and failure modes | Based on customer impact and system-level severity | Most H items → M post-mitigation |
| DFMEA (Design) | Component/subsystem design and failure modes | Based on design effect severity and manufacturing/design controllability | Minimize H; most items → M or L |
| PFMEA (Process) | Manufacturing process failure modes and control points | Based on process failure severity and detection during production | Minimize H; most items → L (well-controlled processes) |
Custom Field Configuration
Action Priority is stored in the following custom fields on Failure Mode work items:
| Field Name | Data Type | Default | Used In | Calculation Trigger |
|---|
premitigationAP | Enumeration (H/M/L) | L | FMEA analysis worksheets, pre-mitigation risk ranking | Risksheet formula (on-demand) |
postmitigationAP | Enumeration (H/M/L) | L | Risk control tracking, Safety Readiness Scorecard | Risksheet formula (post-control assessment) |
- Read Severity, Occurrence, and Detection values
- Apply threshold logic (see Determination Logic section above)
- Return H, M, or L
- Apply cell decorator formatting (colors, text size, labels)
Example: AEB System FMEA
Failure Mode: Loss of Radar Sensor Signal
| Metric | Pre-Mitigation | Post-Mitigation | Notes |
|---|
| Severity | 9 (Safety-critical; AEB cannot function) | 9 (unchanged — effect remains severe) | Severity is inherent; controls cannot change it |
| Occurrence | 6 (Occasional; connector corrosion possible in salty environments) | 2 (Remote; sealed connector + conformal coating) | Prevention control reduces occurrence |
| Detection | 8 (Poor; failure not detected until crash occurs) | 3 (Good; diagnostic self-test during system startup) | Detection control improves with BIT (Built-In Test) |
| Pre-mitigation AP | H (S=9 triggers H automatically) | — | Immediate mitigation required |
| Post-mitigation AP | — | M (S=9 but O=2, D=3 → moderate risk remains) | Residual risk acceptable after mitigation |
- Prevention: Specify sealed connector with conformal coating (reduces occurrence from 6 → 2)
- Detection: Add power-on self-test (PBIT) that verifies sensor communication (improves detection from 8 → 3)
- Risk Control: Create riskControl work item “Implement sealed sensor connector and PBIT” with design engineer assigned
- Verification: After controls validated, post-mitigation AP remains M; document in Design FMEA for component-level analysis
Integration with ISO 26262 and IATF 16949
- ISO 26262 (Functional Safety): Action Priority aligns with Automotive Safety Integrity Level (ASIL) requirements; high ASIL items are typically assigned H priority
- IATF 16949 (Quality Management): Action Priority supports special characteristic (SC) and critical characteristic (CC) classification; characteristics linked to H-priority failure modes may be flagged as SC
- AIAG-VDA FMEA-4: Action Priority implements the 7-step FMEA methodology with structured risk evaluation thresholds
Best Practices
-
Complete All Ratings Before AP Calculation: Do not rely on partial S/O/D data. Complete severity, occurrence, and detection assessments before calculating AP.
-
Team Review of H-Priority Items: High-priority failure modes should be reviewed with the full team (design, manufacturing, quality) to ensure mitigation strategies are feasible and effective.
-
Post-Mitigation Verification: After implementing risk controls, update post-mitigation O and D ratings only if controls have been validated or are planned. Do not artificially lower ratings.
-
Residual Risk Communication: Use post-mitigation AP to communicate final risk status to stakeholders. Residual M or L items should be justified if not eliminated.
-
Phased Closure: Organize corrective action closure in phases (H items first, then M, then L) to manage project resource constraints while maintaining safety priority.
-
Audit Traceability: Link each failure mode to its risk controls and supporting evidence (design reviews, test reports, PBIT specifications) for regulatory audit compliance.
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