How to Verify Used Industrial Parts: Counterfeit & Scam Checklist

The surplus market has genuine decommissioned gold and polished junk. Eight checks tell you which one is on your bench.

Quick diagnosis table

SymptomLikely causeAction
Part works but fails after weeksAged capacitors not replaced in refurbAsk for capacitor/refresh records
Screen prints look uneven or fuzzyRemarked or counterfeit boardCompare label font and layout with OEM photos
Much cheaper than marketSalvaged from scrap or non-workingRequest functional test report before payment
No serial or wrong formatFake or remarkled unitCross-check serial with OEM records
Firmware revision mismatchWrong variant for your applicationConfirm revision against your existing module

Step-by-step procedure

  1. Verify the part number character by character — a single wrong digit (e.g. 1756-IB16 vs 1756-1B16) is the most common wrong-ship.
  2. Check the label: OEM labels are machine-printed with consistent fonts; uneven, hand-typed or fuzzy labels are a red flag.
  3. Cross-check the serial number format against the OEM's numbering scheme; mismatched formats suggest a remarkled board.
  4. Ask for the condition grade in writing: new sealed, new surplus, open box, tested used, refurbished — and what each means from this specific vendor.
  5. Require a functional test report: power-up, program load or parameter readback, I/O forcing — not just a visual check.
  6. Ask what was refreshed during refurbishment: electrolytic capacitors, fans, batteries and backlights are the standard wear items.
  7. Insist on photos of the actual unit (not stock photos), including the label and any connector wear.
  8. Buy with a warranty: 12 months is the market norm for tested surplus; a vendor refusing any warranty is telling you something.

Replacement parts & selection notes

Every part we ship follows this checklist: exact MPN verification against your application, label and serial inspection, a written condition grade, bench functional testing (power-up, program/parameter verification, I/O scan where applicable), real photos of the actual unit, and a 12-month warranty. Send us your part list for a quote within 12 hours — see also our used & refurbished parts service page.

Frequently asked questions

Is refurbished the same as used?

No. Used means pulled and tested where possible; refurbished means inspected, repaired and tested to a defined standard — ask what the standard is and what was replaced.

How common are counterfeit PLC modules?

A real problem for popular high-value modules. The label checks, serial format checks and functional test reports above catch most of them.

Can I test a module myself before installing?

For I/O modules yes — a bench power supply and a simple input forcing test. For CPUs and drives, functional testing requires a rack and software; rely on the vendor's test report.

What warranty should I expect on tested surplus?

12 months is the market norm for tested surplus and refurbished parts. Repaired boards often carry a shorter warranty on the repair itself.

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