Knock Sensor: Service and Repair

Knock sensor (KS), replacing

Removing the knock sensor (KS)
Remove the cable from the battery negative terminal. First read Battery, disconnecting Battery Disconnecting.




Remove the intake pipe between the front cover plate and the air cleaner (ACL).

Applies only to B6xx4T




Disconnect the hose between the turbocharger (TC) and the charge air cooler (CAC) at its upper end. Push it to one side.
Disconnect the hose between the intake and the bypass valve on the pipe between the intake and the charge air cooler (CAC).
Remove the hose between the bypass valve and the pipe between the air cleaner (ACL) and the turbocharger (TC).




Disconnect the connectors for the boost pressure sensor and the charge air temperature sensor from the pipe between the charge air cooler and the throttle body (TB).




Remove the pipe between the throttle body (TB) and the charge air cooler.

Remove




- the screws for the knock sensors (KS)
- the tie strap at the connector.
Pull the sensors downwards and past the starter motor bracket at the rear edge.

Installing the knock sensors (KS)
Install the new sensors with the screws in the cylinder block.
Route the cables on the outside of the starter motor bracket.
Align the sensor (looking from the front towards the rear). The cable from the sensor for cylinder 3 = 5 o'clock and from sensor for cylinder 5 = 6 o'clock.
Tighten the knock sensors (KS) to 20 Nm.
Press the knock sensor (KS) connectors together. Check that the wiring is in the correct position. Clamp if necessary.

Applies only to B6xx4T
Install the pipe between the throttle body (TB) and the charge air cooler (CAC).
Install the connectors for the boost pressure sensor and the charge air temperature sensor.
Install the hose for the bypass valve.
Install the hose between the turbocharger (TC) and the charge air cooler (CAC).

Install
- the intake pipe between the front cover plate and the air cleaner (ACL)
- the battery lead. First read Battery, disconnecting Battery Disconnecting.