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Read-method clarity

OBD vs Bench vs Boot: ECU Read Methods Explained

A customer-safe workshop guide to OBD, bench, boot and virtual ECU reads, why read method matters and what information should accompany a file-service request.

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OBD, bench and boot describe different access situations, not interchangeable file formats. The resulting file coverage can depend on the ECU, tool, protocol and whether the read is physical or supplied as a verified virtual read.

A workshop should record the method reported by its tool instead of guessing from the file name or file size. When the method is uncertain, the safest next step is to identify the ECU and confirm the tool protocol before submission or programming.

Method overview

  • OBD: communication through the vehicle diagnostic connection where supported
  • Bench: controller access outside normal in-vehicle communication without opening the ECU where supported
  • Boot: direct controller access that can require ECU opening and a tool-specific procedure
  • Virtual read: a software-matched original supplied through a supported tool workflow
  • Unknown: a valid temporary state that should trigger identification and confirmation

What to record

  • Tool and protocol name shown during the read
  • Whether the file is a full, partial or virtual read when explicitly known
  • ECU label, supplier, family and hardware/software identifiers
  • File name and size without treating either as proof of identity
  • Any tool warning, recovery state or previous programming history

Safety boundaries

  • Do not select a method from vehicle model alone
  • Do not infer read coverage only from file size
  • Do not write a file until controller identity and programming method are confirmed
  • Use stable battery support and follow the tool manufacturer's procedure
  • Keep an untouched original backup before any workshop programming action

Frequently asked questions

Is a bench read always more complete than an OBD read?

Not as a universal rule. Coverage depends on the ECU and protocol. Record the exact method and tool result instead of assuming completeness from the method name.

Can file size identify whether a read is OBD, bench or boot?

No. File size is only one metadata point and cannot prove the controller identity, read method or coverage by itself.

What should I do if the read method is unknown?

Keep the file unchanged, collect ECU and tool identification, and use the read-method advisor or contact MG AutoTech before continuing.

Related technical pages

Interactive read-method advisorECU platform guidesFile readiness checkECU HW/SW identification guide