12 14 600 Removing/replacing knock sensors (N52T)

2011 BMW 550xi 4.4 CSECTION 12 14 600 Removing/replacing knock sensors (N52T)
IMPORTANT: Aluminum-magnesium materials  .
No steel screws/bolts may be used due to the threat of electrochemical corrosion.
A magnesium crankcase requires aluminum screws/bolts exclusively.
Aluminum screws/bolts must be replaced each time they are released  .
Aluminum screws/bolts are permitted with and without color coding (blue).
For reliable identification:
Aluminum screws/bolts are not magnetic  .
Jointing torque and angle of rotation must be observed without fail (risk of damage)  .

Necessary preliminary work: 

  • Read out the fault memory of the DME control unit.
  • Switch off ignition.
  • Remove INTAKE PLENUM .

Unlock connector (1) and remove.

Fig 1: Identifying Connector
G04751293Courtesy of BMW OF NORTH AMERICA, INC.

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

Installation note: 

Replace aluminum screws  .

Tightening torque 13 62 3AZ .

Fig 2: Locating Knock Sensors
G04751294Courtesy of BMW OF NORTH AMERICA, INC.

Installation note: 

Clean contact surface of knock sensors on engine block.

Fig 3: Cleaning Contact Surface Of Knock Sensors On Engine Block
G04748562Courtesy of BMW OF NORTH AMERICA, INC.
RENDER: 1.0x

NO RELATED

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • You smell fuel, burning insulation, or see smoke.
  • Brakes feel soft, pull hard to one side, or make grinding noises.
  • The engine overheats, stalls repeatedly, or misfires under load.
  • You are missing required tools, torque specs, or safe lifting equipment.
  • You are not confident in the next step or safety outcome.