I am replacing my ECM with an ECM I bought on Ebay.

What do these serial numbers on my ECM mean?

P/N 12580204
Serv. No. 12574270
GM03E10A10  ODP48    10032002

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Are these serial numbers software / hardware versions? Should they match the number on the new ECM I bought?


Here is a picture of the ECM I bought on Ebay:

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  • 2
    A "serial number" is a number that is unique per part that comes off of the assembly line. If you made, say, five power steering pumps, they could have serial numbers ("S/N") 1,2,3,4 and 5. If you see two devices with the same serial number, someone is selling fakes or having fun printing stickers.
    – 3Dave
    Dec 9, 2016 at 23:53

1 Answer 1


I can't read the number on the one that you bought, and I don't know any specifics about how Saturn does their numbering, but in general, you might see:

  • Part Numbers: Which tell you "what" the thing is.
  • Serial Numbers: Which tell you who the thing is. Each individual item will have a different serial number. Usually only important things, or things that get meaningful changes on a running basis will be worthy of serial numbers. For "less important" things – for example a connector vs. the ECU a change would result in a change in the part number.
  • Production Codes: These will be numbers or codes to tell you when and where the item was made. They are often not identified, but sometimes you can recognize them by their form – for example they will often have two or four digits that correspond with the year in them.
  • Revision/Version Numbers: Sometimes a device like an ECU will have a single part number and multiple revisions that reflect minor changes that aren't supposed to make it "different" – for example improving the noise protection on the inputs might be the sort of thing that is worthy of a revision/version bump, but not a whole new part number.

Then for devices like an ECU there will, potentially, be markings for both the hardware and the software. Maybe even for multiple software components.

The bottom line is that with something like an ECU it can be quite a challenge to figure out what's what and which of the differences are significant and which are not. This is where it can really help to cultivate good relationships with folks who have access to "official" data.

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