12 14 600 Replacing knock sensor (N12, N14)

Necessary preliminary tasks: 

• Switch off ignition
• Read out fault memory of DME control unit
• Check stored fault messages
• Disconnect negative battery cable. See 61 20 900 DISCONNECTING AND CONNECTING BATTERY NEGATIVE LEAD
• All-wheel drive vehicles only:  Remove intake plenum.

Installation location:

The knock sensor is located under the intake manifold next to the starter motor.

Use a reversible ratchet (1) and extension to release the screw of the knock sensor from below.

Fig 1: Releasing Knock Sensor Screw Using Reversible Ratchet

Courtesy of BMW OF NORTH AMERICA, INC.

Release screw and remove knock sensor (2).

Pull knock sensor slightly downwards until the connector of the knock sensor is accessible. Unlock connector (1) and remove.

Installation: 

Clean contact surface of knock sensor on engine block.

Tightening torque 13 62 2AZ.

Fig 2: Identifying Knock Sensor And Unlock Plug

Courtesy of BMW OF NORTH AMERICA, INC.