ECU Guides

EA189 or EA288: telling EDC17C46, CP20 and C54 from EDC17C64, C74 and MD1CS004 by part number

10 October 2026 4 min read

Two Golfs, both 2.0 TDI, both “EDC17 Bosch”, both on the ramp with the ECU out. One label says 03L997018D, the other 04L906026S. The first is EA189 on EDC17C46, the second is EA288 on EDC17C74, and the files don’t cross over in either direction. Ordering by engine size and model gets this wrong every time. The part number prefix gets it right in two seconds.

03L and 04L: the prefix rule

VAG engine ECU numbers start with a three-character engine family code. 03L is the EA189 common-rail generation (2008 to 2015): 1.6 TDI CAYx, 2.0 TDI CBxx, CFxx, CJxx and so on. 04L is EA288 (2013 to 2019 and, as EA288 evo, into the 2020s). A few outliers exist (the Crafter on 03L997403 with EDC17C54, the A6 2.0 TDI CAG family on EDC17CP14), but the prefix has never pointed at the wrong generation in anything we’ve handled.

Which controller on which generation

  • EA189: EDC17C46 (03L997018, 03L997264 numbers; Golf VI, Octavia II, Tiguan 5N, Passat B7, Leon 1P, A3 8P), EDC17CP14 (A4 B8 and A6 2.0 TDI; the same controller also runs the Touareg 7L V6, which isn’t EA189), EDC17CP20 (T5.1, Amarok, Crafter BiTDI, A4 and A5 B8 later), EDC17C54 (Crafter 2.0 TDI).
  • EA288: EDC17C64 (04L997021 and 04L997022; Golf VII, Octavia III, Leon 5F, A3 8V, A6 C7 ultra), EDC17C74 (04L906026; Passat B8, Golf VII facelift, Tiguan II, T6), MD1CS004 (EA288 evo from 2018; Golf VIII, Octavia IV, Passat B8 facelift, Tiguan II facelift on most versions).

From the catalogue:

  • VW GOLF EDC17C46 03L997264M 2048 1037519336
  • SKODA OCTAVIA EDC17C46 03L997264N 2049 1037519337
  • VW TIGUAN EDC17C46 03L997264P 2050 1037519338
  • SKODA OCTAVIA EDC17C46 03L997018 9977 1037560941
  • VW GOLF EDC17C46 03L997018D 9979 1037561782
  • SKODA OCTAVIA EDC17C64 04L997021 1646 10SW000811
  • AUDI A6 EDC17C64 04L997022A 3913 10SW013728
  • VW PASSAT EDC17C74 04L906026 3162 10SW009685
  • VW ALL EDC17C74 04L906026S 3163 10SW009686

Why the files can’t be swapped

It isn’t a checksum or a tool limitation. EA288 changed the injection pressure and injectors, moved to a combined high and low pressure EGR, added a close-coupled DPF with a NOx trap or SCR, and uses different sensors on the intake and exhaust. The ECU hardware differs too: C46 is a TC1767 unit with 2 MB of flash, C64 and C74 are TC179x with 4 MB. An EA189 file has no maps for hardware that isn’t there, and the reverse file expects sensors the EA189 never had. Even within EA288, C64 and C74 are not the same box, and a 1.6 file in a 2.0 is a limp-mode car with the wrong injector coding.

Software campaigns and the version number

The four digits after the VAG number are the software version, and on EA189 they matter more than usual because of the 2016 to 2017 emissions update campaign (the 23R7 family of actions and its follow-ups). A Golf that was 2048 before the campaign came back as a 99xx version afterwards on most cars. The coding, the dataset and the checksum area are all tied to that version, so an original 2048 file won’t sit right in an ECU updated to 9979, and the other way round, even though the VAG number is unchanged. EA288 had its own updates (the 23X4 campaign on 2.0 TDI, plus SCR-related ones), which is why the C64 and C74 lists carry three or four versions per suffix.

Read the version with VCDS or ODIS (it’s in the engine module identification) or from the flashing tool’s ID screen before you order. If you’re restoring a car after a failed tune and don’t know whether the campaign was done, the coding block in a bench read tells you. If you need the dealer flash container itself rather than a read, that’s an FRF or SGO job, which is a separate thing.

Which file to order

  1. Photograph the label: prefix (03L or 04L), the full number with suffix, and the Bosch 0281 number. The label guide shows where each sits.
  2. Read the software version and Bosch ID (1037 or 10SW) with VCDS or the tool.
  3. Note SCR or not on EA288, and whether the car has been through a campaign on EA189.
  4. Pick the model page (C46, CP14, CP20, C54 for EA189; C64, C74, MD1CS004 for EA288) and match all three numbers.
  5. If nothing matches, send your own read; we can usually pull the exact version.

EA189 stock reads are on the EDC17C46 page and its neighbours, EA288 on the EDC17C64 and MD1CS004 pages. For anything not listed, the request form with the label photo and your read is the fastest route.

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