Error-proofing (IATF only)
Plain-language summary
Error-proofing is a documented, planned discipline: opportunities identified in the FMEA process, devices tested per the control plan with failures triggering reaction plans, and challenge parts controlled like gauges.
What the clause is really asking
Determine the use of error-proofing methodologies within your process (documented). Details documented in the PFMEA; test frequencies in the control plan. Error-proofing device failures get a reaction plan; challenge/master parts used to verify devices are identified, controlled, verified and calibrated where feasible — with records.
What auditors look for
Auditors find an error-proofing device and ask: where is it in the PFMEA? Test frequency in the control plan? Show me this week's verification with the challenge part — and the challenge part's own control record. Device failure last month: reaction plan evidence?
Typical evidence
PFMEA entries for error-proofing; control plan verification frequencies; challenge part register with control/calibration; device failure reaction records.
How to comply — recommendations
Register every poka-yoke like an instrument: ID, location, verification method, frequency, challenge part. Verify at shift start with the red-rabbit part and log one line. Link device failure directly to your 8.5.6.1.1 bypass list — same event, two clauses, one procedure.
Common nonconformities
Devices never verified (assumed working for years); challenge parts lost or uncontrolled; error-proofing absent from PFMEA; failed device bypassed informally.
Related clauses
Builds on ISO 9001 10.2; links IATF 8.5.6.1.1
In the book
Chapter 10 — Improvement — Closing Loops for a Living treats this clause family in full: what it is really asking, what auditors look for, the evidence that satisfies, how to make it work on a real floor, and where companies stumble. This IATF requirement is covered in the Automotive Edition, in the same six blocks as the ISO clause around it.
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Qlause provides interpretive guidance only and is not a substitute for the standard. Refer to your licensed copy of the relevant standard for the authoritative text.