12 51 100 Replacing wiring harness section for ignition and injectors (N54)

IMPORTANT: Aluminium screws/bolts must be replaced each time they are released.
Aluminium screws/bolts are permitted with and without color coding (blue).
For reliable identification:
Jointing torque and angle of rotation must be observed without fail (risk of damage).

IMPORTANT: Read and comply with notes on PROTECTION AGAINST ELECTROSTATIC DAMAGE (ESD PROTECTION) .

Necessary preliminary tasks:

Read out fault memory of DME control unit
Switch off ignition
Clamp off BATTERY NEGATIVE LEAD
Remove CLEAN AIR PIPE
Remove rear IGNITION COIL COVER

Release bolts (1).

Tightening torque 12 90 2AZ .

Remove electronics box cover (2).

Fig 1: Identifying Electronics Box Cover And Screws

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Unlock all plugs (1) from control unit and disconnect.

Unclip grommet holding-down element (2) and remove.

Release rubber grommets (3) from electronics box. Lay wiring harnesses to one side.

Installation:

Make sure rubber grommets are correctly seated (watertightness).

Fig 2: Identifying Rubber Grommets, Grommet Hold-Down Device And Connectors

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Unclip oxygen sensor cable from retainer (1) and lay to one side.

Release nuts (2) and remove grounding cable.

Tightening torque 12 90 5AZ .

Unlock all plugs from ignition coils and injectors and detach.

Unclip wiring harness (3), feed out and remove.

Fig 3: Identifying Wiring Harness And Nuts

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NOTE: Check stored fault messages.
Now clear the fault memory.