Bosch ME7 is the engine control unit (ECU) that ran most of Volkswagen Auto Group's 1.8 turbo cars from roughly 1999 to 2006 — the Mk4 Golf GTI, the B5 Passat 1.8T, the Audi A4 / A6 B6 / B7 1.8T, the early Audi TT 8N, and the Seat Leon Cupra / Skoda Octavia RS. Twenty years on, those cars are landing in the third-and-fourth-owner aftermarket where the immobilizer chain is one of the most common failure points. The fix — IMMO-OFF — is a 4-byte arithmetic patch to the ECU's EEPROM that disables the immobilizer check.
The hard part isn't the patch itself. It's figuring out which ME7 variant you're holding so you apply the right patch. Bosch shipped dozens of ME7 sub-revisions across VAG + non-VAG vehicles, and the EEPROM byte-layout differs by revision. The Hella sticker on the ECU case is the primary identification tool. This guide walks through how to read it.
What's on a Bosch ME7 Hella sticker
The Hella sticker is the small white-or-silver adhesive label on top of the Bosch ECU case. It carries 3 lines that matter for IMMO-OFF identification:
- The 10-digit Bosch part number.Format “0 261 207 XXX” (newer ME7 hardware) or “1 037 372 XXX” (older ME7 hardware). The first 7 digits are the Bosch family; the last 3 are the calibration-specific suffix.
- The VAG-side part number.Format “06A 906 032 XX” or similar — the part number that VAG (Volkswagen / Audi / Seat / Skoda) uses internally. This is the number the VAG dealer parts catalog will hit on.
- The hardware/software revision code.A short alphanumeric like “HW0001/SW0036” or “ME7.5 HW3.10 SW0001”. This is the most useful for IMMO-OFF — it tells you the ME7 sub-family.
For an exhaustive Hella-sticker decoding reference, the long-running compendium at Nefarious Motorsports' ME7 reference thread catalogs hundreds of ME7 part numbers against their VAG applications. Cross-reference your sticker against that thread + against our coverage matrix at /coverage to find your variant.
The ME7 sub-family map
ME7 ships in roughly 5 sub-families relevant to VAG IMMO-OFF work:
- ME7.1 — early VAG 1.8T (Audi A4 B5, Passat B5). Mostly retired now; we still patch the 06A 906 018 GP / GG / DT variants when they come in.
- ME7.1.1 — Audi V6 derivatives. Edge case for VAG-side IMMO-OFF; usually a different patch flow.
- ME7.5 — the dominant ME7 variant for VAG 1.8T: Mk4 Golf GTI, Mk4 Jetta 1.8T, B5.5 Passat 1.8T, Audi A4 B6 1.8T, Audi TT 8N 1.8T. This is the bread-and-butter family for ME7 IMMO-OFF requests.
- ME7.5.20 — facelift of ME7.5 with revised immobilizer routine. Same patch family but byte addresses shifted.
- ME7.6 — V8 + V10 variants (Audi RS4 B7, S4 B7). Different patch flow; covered in our V8/V10 deep dive.
Layout-a vs layout-b — what they mean
Within ME7.5, Bosch shipped two distinct EEPROM byte-layouts for the immobilizer secret. We call them layout-a and layout-b. The arithmetic patch is the same in both: a 4-byte +1/-1/+1/-1 operation that XORs out the immobilizer-active flag. The difference is the byte addresses:
- Layout-a: patch addresses 0x02, 0x0E, 0x12, 0x1E within the 512-byte EEPROM.
- Layout-b: patch addresses 0x12, 0x1E, 0x22, 0x2E — the entire block shifted by +0x10 due to Bosch renumbering the EEPROM map mid-revision.
Applying layout-a addresses to a layout-b dump produces a file that writes garbage to the wrong addresses + leaves the immobilizer-active flag in place. The vehicle still won't start, and the dump has been corrupted in the process — which is why we always run the free /identify check before patching to confirm which layout you're holding. The check is instant, free, and tells you definitively which layout matches your file.
What changes inside the ECU when we IMMO-OFF a ME7
The full patch sequence for a Bosch ME7.5 layout-a IMMO-OFF:
- Read the 512-byte EEPROM via OBD-II (with the proper Bosch ME7 read tool) or via bench-mode K-line + eeprom programmer.
- Patch 4 bytes at the layout-a addresses (0x02, 0x0E, 0x12, 0x1E). Each byte is incremented or decremented by 1 relative to its original value in a specific alternating pattern. The total byte modification per file: 4 bytes out of 512.
- Checksum recovery for the EEPROM tail (ME7 has 2-3 checksum sectors stored in the last 16 bytes). Automated solver, takes milliseconds.
- Verify against the known-good post-patch checksum signature for the variant. If verify fails, halt + flag for human review.
- Writethe patched 512-byte file back to the ECU's EEPROM via the same K-line or bench-mode path.
After write-back, the ECU reads the modified EEPROM on boot, sees that the immobilizer-active flag is no longer set, and skips the entire transponder challenge sequence. The vehicle starts with any cut key (or no transponder at all on the older immobilizer-II spec).
What ME7 IMMO-OFF does NOT do
- Does not affect emissions. The immobilizer check is a discrete EEPROM read in a separate code path from fuel injection, ignition timing, or any emissions-related calibration. Vehicle passes inspection identically before and after.
- Does not affect the cluster IMMO light. The dashboard IMMO indicator runs off the cluster + BCM, not the ECU. After IMMO-OFF the light may still flicker on key-on but the vehicle starts anyway. Some customers prefer to delete the cluster IMMO signal too; we cover that in a separate IMMO-OFF-and-cluster guide.
- Does not work on every ME7 sub-revision.Specifically ME7.5 GT variants (some 2003-2004 mid-cycle builds with a Bosch hardware-secured immobilizer module) need a different patch flow. The free identifier flags these before you pay.
Pricing — 2026 numbers
Independent ME7 IMMO-OFF services typically charge:
- $25 per file for the dominant ME7.5 layout-a and layout-b variants we have validated byte-level patches for. Confirmed-coverage entries are marked Live in our /coverage matrix.
- $15 per file effective when buying credit packs (e.g., $200 for 10 credits, $750 for 50). High-volume tuners + locksmiths almost always run on packs.
- $50-100 per file for less-common ME7 revisions where the patch is donor-pair-derived per job. Rare on the mainstream VAG variants but occasionally needed on regional-spec ECUs (Argentine + Brazilian + Eastern European calibrations).
Compare to the dealer alternative for the same outcome:
- New ECU from VAG: $400-1,200 (varies wildly by region + part availability — B5 Passat ME7s are often discontinued)
- Dealer programming: $300-500
- Key + immo-cluster pairing: $200-400
Total dealer cost: $900 - $2,100. Total independent IMMO-OFF: $25. The math has driven 95%+ of the VAG 1.8T community to the IMMO-OFF route for any swapped-ECU or lost-key scenario.
As one veteran VAG specialist put it:
“Mk4 Golf GTI customer brings me a salvage-yard ME7 he bought for $80. Five years ago I would have told him to go to the dealer. Today I bench-read it in 10 minutes, send the EEPROM dump to ECU Flash Cartel, get the patched file back before lunch, write it back, install, start the car. Total labor 90 minutes, customer pays me $250, I keep the spread.” — Independent VAG specialist, ECU Flash Cartel customer
The Bosch sticker mistake — what to avoid
The single most common identification mistake we see: customers reading the VAG part number (06A 906 ...) and assuming it uniquely identifies their ECU. It doesn't. The same VAG part number ships with multiple Bosch internal hardware revisions over the production run, and the byte layout follows the Bosch revision — not the VAG part number.
Always cross-reference the Bosch 10-digit part number (0 261 207 XXX or 1 037 372 XXX) against the variant database. The free identifier at /identify reads the firmware-embedded fingerprint and tells you the exact Bosch revision regardless of what the Hella sticker claims (occasional cases of mis-stickered ECUs from VAG's warranty replacement program).
Companion reading
- What is IMMO-OFF — when do you need it — the broader IMMO-OFF service this ME7 patch is a special case of
- MED17 IMMO-OFF guide for VW / Audi MK6 MK7 — the successor to ME7 on VAG cars; same product line, different patch flow
- ECU checksum repair service guide — why the post-patch checksum step matters
- Live coverage matrix — every ME7 variant we patch, with honest status flags