Mercedes CRD3 ECU Files: OM651 C-Class, E-Class, Sprinter and Vito Original, Immo Off and Virgin

The Delphi CRD3 family controls the Mercedes OM651 2.1 CDI diesel used from 2008 in the C-Class W204/W205, E-Class W212, GLK, ML W166, Sprinter W906, Vito W639/W447 and the Infiniti Q50 2.2d. The label shows a variant such as CRD3.10, CRD3.20, CRD3.50, CRD3.7A, CRD3.E1 or the later CRD3P.B0 / C0. Each variant has its own files, so identification comes first.

FBS: the Mercedes immobilizer

Mercedes pairs the engine ECU with the EZS (ignition switch) and the key through FBS3 (older) or FBS4 (W205/W447 onward). A used CRD3 from another car does not start the engine: Xentry reports the ECU as “personalised” to a different vehicle. Options:

• Virgin file — resets the FBS personalisation so Xentry/DAS can personalise and activate the ECU on your car (dealer online step or an offline tool for FBS3). The correct route for a road car.
• Immo off — the ECU no longer checks the EZS. For engine swaps, marine and industrial use, or when the EZS is unavailable. On FBS4 cars immo off is limited to certain software versions.
• Original file — full stock read for recovery after a failed flash or to remove a tuned map before a dealer visit.

Reading the CRD3

1. Bench: KTAG, Flex and New Trasdata read the CRD3.x (TriCore TC1797/TC1793) in bench mode via the connector; CRD3P versions are supported by Flex and New Trasdata.
2. OBD: KESS V2/KESS3 and Autotuner handle many CRD3 versions over OBD for writing; a virtual read is used on locked versions, so keep a bench original for safety.
3. Record the Mercedes part number A 651 900 xx xx and the Delphi variant; both must match the file.

Writing and afterwards

Checksums are valid in the files. After a virgin file, complete the personalisation and activation in Xentry before the first start. After immo off, the engine starts immediately; the EZS may still log a mismatch that Xentry displays but that does not block driving.

Workshop notes

• Sprinter and Vito CRD3 files differ from passenger-car versions (rev limits, gearbox strategy); do not cross them.
• A CRD3 replaced without injector coding (IMA) runs rough — enter the codes in Xentry afterwards.
• Keep the vehicle on a stabilised supply; the CRD3 is sensitive to voltage drops during long OBD writes.

Find your version

Browse the whole family under CRD3, or directly CRD3.10, CRD3.20, CRD3.7A and CRD3P.B0, or start from the Mercedes-Benz brand page. Missing part number? Use the file request form.