12 14 550 Replacing control unit (DME) (N55)

Necessary preliminary tasks: 

• Switch off ignition.
• Disconnect BATTERY NEGATIVE LEAD .
• Remove INTAKE PLENUM .

Replacement: 

• Carry out programming/encoding
• If no data can be read out from the previous control unit, carry out injection quantity compensation (description at end of instructions).

Switch off ignition.

Release screws (1).

Tightening torque 12 14 2AZ .

Release screws (1).

Tightening torque 12 14 1AZ .

Remove control unit from intake plenum.

Installation note: 

Renew gasket between intake plenum and control unit.

Injection quantity compensation: 

If the DME control unit has been replaced, it will also be necessary to carry out adjustment of the injectors!

Injection quantity compensation is carried out with the aid of so-called adjustment values.

The adjustment value is printed on each injector in three digits.

If necessary, remove EMC panel.

The adjustment values must be stored in the new control unit!

If injector quantity compensation is not carried out, the engine may run roughly or fail to start.

Read off the adjustment values and enter according to the installation location (cylinder) of the injectors:

• Connect BMW diagnosis system
• Identify vehicle
• Select "Function selection"
• Select "Service functions"
• Select "Engine electronics"
• Select "Adjustment function"
• Select "Adjust injectors"
• Select "Test plan"
• The adjustment value must be entered for each cylinder.
  Fig 3: Identifying Injector Adjustment Value

  Courtesy of BMW OF NORTH AMERICA, INC.