E46 only

Remove microfilter.

Open cable duct on lower section of microfilter housing (2) and feed out cable(s).

Release screws (1) and remove lower section of microfilter housing (2).

Fig 1: Releasing Screws & Removing Lower Section Of Microfilter Housing

Courtesy of BMW OF NORTH AMERICA, INC.

Remove cover from fuel injectors.

Mark plug connections.

Unclip the cable from the retainer. Disconnect plug. Unclip cable on rear side of engine from cable guide.

Fig 2: Unclipping Cable From Retainer

Courtesy of BMW OF NORTH AMERICA, INC.

In event of unfavorable tolerances, accessibility to the oxygen monitor sensor from cylinders 4 to 6 is only possible after the exhaust system has been removed.

Release oxygen monitor sensor from cylinders 1 to 3 with special tool 11 7 030.

Release oxygen monitor sensor from cylinders 4 to 6 with special tool 11 7 020.

Fig 3: Releasing Oxygen Monitor Sensor From Cylinders

Courtesy of BMW OF NORTH AMERICA, INC.

Installation: 

The threads of new oxygen monitor sensors are already coated with Never Seez compound.

If an oxygen monitor sensor is reused, only apply a thin and uniform coat of Never Seez compound (refer to BMW Parts Service) to thread.

Part of oxygen control sensor which projects into exhaust system branch must not be cleaned or come into contact with lubricant.

Installation: 

Secure oxygen monitor sensor for cylinders 1 to 3 with special tool 117 030.

Secure oxygen monitor sensor for cylinders 4 to 6 with special tool 117 020.

Tightening torque. Refer to ENGINE - TIGHTENING TORQUES .

Cover oxygen monitor sensors when applying underseal.

Pay attention to cable routing of oxygen monitor sensors.

Fig 4: Securing Oxygen Monitor Sensor For Cylinders

Courtesy of BMW OF NORTH AMERICA, INC.