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VAG ECU Part Numbers on Golf, Passat, A4 and Q7: Software Versions and 997 vs 906 Numbers

30 October 2026 4 min read

Golf VI 2.0 TDI, EDC17C46, customer wants the file for a used ECU he was sold as ‘the same’. His original label: 03L997018B, 9978, 1037561781. The replacement: 03L997264P, 2050, 1037519338. Both are EDC17C46, both 2.0 TDI, and they are not the same file. Reading a VAG label properly takes about a minute and saves that kind of mistake.

Three numbers, three jobs

A VAG engine ECU label carries the VAG part number, a four-digit software version and a Bosch (or Siemens/Continental) software reference. Using the Golf above:

  • 03L997018B is the VAG part number. 03L is the engine family (2.0 TDI common rail, EA189), 997 018 is the component and revision block, B is the index letter.
  • 9978 is the software version. It’s the number ODIS and VCDS show as software version, and it counts upward with every update.
  • 1037561781 is the Bosch software number. It changes whenever the version changes.

Other prefixes you’ll meet: 04L for the EA288 diesel (04L997022A 3913 10SW013728 on an A6 EDC17C64, 04L906026 3162 10SW009685 on a Passat EDC17C74), 03C and 04E for the small TSI engines (03C997016 8642 1037514973 on a Golf MED17.5.5, 04E906016 7700 1037543627 on MED17.5.21), 8K5 for the A4/A5 B8 (8K5907589 0004 1037544652, EDC17CP44), 4M0 for the current Q7 (4M0907401 0006 10SW018739, EDC17CP54), 0AM for the DQ200 mechatronic (0AM927769D with gearbox 0AM300050P, version 9030).

906 versus 997: replacement part numbers

The middle block is 906 (906 016, 906 021, 906 026, 906 027, 906 056) on parts as fitted at the factory. A 997 number in the same position (997 018, 997 022, 997 027, 997 403) is a replacement or update part number, issued when VAG released a software fix or a service replacement ECU. The Crafter EDC17C54 in the catalogue is a good illustration: 03L997403 exists with version 5814 (1037536216) and 9978 (1037561045), and 03L997403R with 5830 and 9978. The two Golf numbers above are two 997 branches; on most versions they belong to different engine codes, so check the engine code on the label as well.

Practical consequence: a used ECU with a 906 number can be running 997 software after a dealer update, and the sticker won’t say so. Always read the ident with VCDS or ODIS before you compare labels.

907 in place of 906 (8K5907589, 4M0907401, 8P0907115BC, 1P0907115) is just a different component group used mostly on Audi and on newer diesels; it follows the same rules.

The four-digit version and what it tells you

Versions run in families. On the EDC17C64 the 04L997021H appears at 3084 (10SW010639) and 3912 (10SW013729); the 04L997022A at 3096 and 3913. On the EDC17CP44 the plain 8K5907589 goes 0004, 0006, 0008; the 8K5907589C sits at 0004 and 0005 with 10SW numbers. The same version can exist on two neighbouring part numbers with different Bosch numbers, so version alone isn’t enough; part number plus version is. A jump like 5814 to 9978 on the Crafter is a major release, and on most EA189 cars the 99xx versions are the emissions recall software. The 9978 file will not be happy on a car whose gearbox or EGR variant expects the older one.

10SW versus 1037

These are both Bosch software references. 1037 numbers run to roughly 2013 and 10SW takes over afterwards; a label with 10SW is simply newer. Nothing else changes. Siemens/Continental VAG boxes (Simos, PCR2.1) don’t use either and rely on the VAG number plus version.

Ordering the right file: procedure

  1. Note the VAG part number including the index letter (03L997018B, not 03L997018).
  2. Note the four-digit version from the label and confirm it with VCDS/ODIS. If they differ, the diagnostic reading wins.
  3. Note the 1037 or 10SW number.
  4. Search the version and part number together. Product titles in the catalogue are written in exactly this order: part number, version, Bosch number.
  5. If your version isn’t there, the nearest lower version on the same part number is usually safe as a stock file for testing; the nearest higher one is not, because it may need matching gearbox or instrument cluster software.

What a stock file won’t do on VAG: it won’t fix component protection (needs online ODIS), it won’t pair a used ECU to the immobiliser (immo 4 needs key adaptation with VCDS/VCP or a virgin file; immo 5 mostly needs online access), and a DSG file needs the gearbox part number too (0AM927769K with 0CW300046 on an A3, 0AM927769G with 0CW300044T on a Leon).

Search by version on the EDC17C46, EDC17CP44 or EDC17C64 pages, or by brand under VW. Missing version? Send part number, version and a VCDS screenshot through the request form.

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