11 78 540 Replacing Left Monitor Sensor

11 78 540 Replacing left monitor sensor (N74)

Special tools required:





Warning!
Scalding hazard!
Only perform this work after engine has cooled down.





Necessary preliminary tasks:
^ Check function of DME control unit
^ Turn off ignition
^ Remove rear underbody protection





Remove heat shield (2) of the left side.





Release exhaust system (1) at the catalytic converters.

Remove (2) sealing ring.





Release screws (1).

Remove exhaust holder (2).

Tightening torque: 18 31 3AZ.





Unclip plug connection (2) of the oxygen sensor from the holder (1).

Release oxygen sensor cable (3) from the retaining clips (4).

Disconnect plug connection of the oxygen sensor (2).





Detach oxygen sensor cable (1) from the retaining clips (2).





Release monitoring sensor (1) with special tools 11 7 030 and 11 9 150.





Installation:
The threads of new lambda control/monitoring sensors are already coated with Never Seez Compound (refer to BMW Parts Department).

If a lambda control/monitoring sensor is to be reused, apply a thin and even coating of Never Seez Compound to the thread only.

The part of the lambda control/monitoring sensor which projects into the exhaust branch (sensor ceramics) must not be cleaned and not coated with lubricant.





Fasten monitoring sensor (1) with special tools 11 7 030 and 11 9 150.

Installation:
When special tool 11 9 150 is used in conjunction with special tool 11 7 030, 47 Nm on the torque wrench dial corresponds to an actual tightening torque of 50 Nm.

Tightening torque 11 78 1AZ.





Installation:
Check function of DME control unit.

Pay attention to cable routing of monitor sensor.