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IMMO-off patch in bench_read_original_immo.bin breaks ECU functionality (Simos18.1, 8S0906259, SW 0005) #10

@Brucki4

Description

@Brucki4

Hi,

I followed the workflow from your tune-editor / simos12-to-simos18-conversion repo for an IMMO-off on a Simos18.1 ECU (8S0906259), and the resulting bench_read_original_immo.bin leaves the ECU in a partially broken state.

Setup:

ECU: Simos18.1, Spare Part Number 8S0906259, Software Version 0005
Bootloader Identification: SC8.1 CB.00.00.C0 C02.00 SC8
Engine: CHHC (Audi TT-S 2.0l R4 TFSI)
Workflow used:

BSL erase_sector 80800000 (ASW3 erase to enter CBOOT recovery)
flash_unlock with FL_8V0906259H__0001.frf (Sample Mode active, X13 confirmed)
flash_bin with the provided bench_read_original_immo.bin (and also tried with pre-checksum-fixed version)
Diff between original bench read and patched IMMO file:

Only 4 bytes changed: ASW1 @ 0x123B48
Original: 39 F2 84 60
Patched: BB 80 05 20
No other changes (no CBOOT patch, no CAL data changes)
Result after flash:

get_ecu_info shows the basic identifiers correctly:

Hardware Number ✓
Spare Part Number 8S0906259 ✓
Application Software Version 0005 ✓
Hardware Version: H13
But several DIDs that work on a stock flash come back empty / RequestOutOfRange (0x31):

VW System Name Or Engine Type: (empty)
Engine Code Letters: (empty, should be CHHC)
VW Coding Repair Shop Code: (empty)
VW Coding Value: (empty)
Also get_dtcs fails with ServiceNotSupported (0x11).

When I reflash the original FL_8S0906259___0005.frf (no IMMO patch), all DIDs come back correctly (CHHC, 2.0l R4 TFSI, full Coding Value, etc.). So the 4-byte ASW1 patch at 0x123B48 appears to overwrite something it shouldn't for this software version, leaving the ECU partially non-functional.

Could you verify whether the patch address / patch bytes are correct for SC8.1 software 0005, or provide an updated IMMO-off bin that targets this version specifically?

Thanks!

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