Knock Sensor: Service and Repair

12 14 600 - Removing/replacing knock sensors (N52, N52K, N51)





Important!
Aluminium-magnesium materials.
No steel screws/bolts may be used due to the threat of electrochemical corrosion.
A magnesium crankcase requires aluminium screws/bolts exclusively.
Aluminium screws/bolts must be replaced each time they are released.
Aluminium screws/bolts are permitted with and without colour coding (blue).
For reliable identification:
Aluminium screws/bolts are not magnetic.
Jointing torque and angle of rotation must be observed without fail (risk of damage).





Necessary preliminary tasks:
- Read out fault memory of DME control unit
- Switch off ignition
- Clamp off battery negative lead 61 20 900 Disconnecting and Connecting Battery Negative Lead
- Remove intake air manifold Service and Repair





Unlock plug (1) and remove.





Release screws on both knock sensors (1) and remove knock sensors (1).

Installation Note:
Replace aluminium screws.
Tightening torque 12 14 1AZ [1][2]Specifications.





Installation Note:
Clean support face of knock sensors on engine block.





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