Injector Classification - AH07.16-P-1001-01B

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Engine 611.960/961/962, 612.961/962/965/966/990, 640

Fig 1: Identifying Injectors And Control Unit

Courtesy of MERCEDES-BENZ USA

Compatibility:
	Control unit DK below 0/5	Control unit DK 0/5 and higher	Control unit requires adaptation
Unclassified injector	X	X
Classified injector		X	X

The classification can only be clearly recognized or assigned via the diagnosis identifier (DK) 0/5 and above (refer to DAS, CDI 2, control unit version).

The classification of injectors into 3 levels reflects the fuel metering characteristics of the injectors. This will make it possible to adapt the engine software across smaller incremental ranges to injector tolerances.

When installing or replacing the injector or the engine control unit, the following points must be taken into account as a general rule in future:

Injector

Classified injectors can be recognized by the part number and the identification on the magnetic head (circle with a number between 1 and 3 inside). That number indicates the classification level.
When replacing an injector the spare part needs to be ordered as specified by the diagnosis identifier.
After an injector has been replaced on a vehicle with a diagnosis identifier of version 0/5 or higher, the category number must be assigned to the matching cylinder in the CLASSIFICATION menu item by the DAS during control unit adaptations.

From version DK 0/5 onwards, it is also possible to shut down individual injectors for diagnostic purposes when the engine is running. In this case, the classification must be noted down in advance, otherwise the cylinder head cover has to be removed to read the classification level.

Engine control unit

Engine control units are downward compatible with all models down to and including CDI 2. Default setting for the engine control units is level 2. When a control unit with identifier DK 0/5 and above is fitted to a vehicle with DK below 0/5, a version coding test is additionally required.

These boundary conditions also apply when for example, due to engine replacement or repairs to the cylinder head etc., the cylinder-specific assignment of injectors or even the assignment of engine control units may change.

If classification for vehicles with DK 0/5 and above is ignored, it might give rise to complaints such as smoke formation, unbalanced or bucking engine run, and performance deterioration.