Knock Sensor: Service and Repair

12 14 600 - Removing/replacing knock sensors (N54, N53)





Special tools required:
- 13 5 281
- 13 5 282
- 32 1 270 32 1 270 Plugs (Set)





Warning!
Disconnect battery negative terminal Disconnecting and Connecting Battery Negative Lead (risk of fire due to short-circuiting on removal).

Electric fuel pump starts up automatically when door is opened!

Carry out installation work on fuel system only with coolant temperature below 40 °C.





Important!
Adhere to conditions of absolute cleanliness when working on the high-pressure fuel system.

Introduced contaminants can cause malfunctions in the system!

- Do not allow any dirt particles or foreign bodies to get into the system.
- Remove all traces of dirt before removing pipes or individual components.
- Use only fluff-free cloths.
- Seal all fuel system openings with protective caps or plugs.





Important!
Aluminium screws/bolts must be replaced each time they are released.

Aluminium screws/bolts are permitted with and without color coding (blue).

For reliable identification:

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
- Remove intake air manifold Service and Repair

Note:
Illustration shows N54.





Recycling:
Fuel escapes when fuel lines are detached.

Catch and dispose of escaping fuel.

Observe country-specific waste-disposal regulations.





Unlock plug (1) and remove.

Unlock and detach fuel line (2).

Catch and dispose of escaping fuel.





Seal fuel lines with special tools 13 5 281 and 13 5 282.





Slacken nut (1).

Close off fuel line connection of high-pressure pump with a matching plug from special tool kit 32 1 270 32 1 270 Plugs (Set).

Release screw (2).

Installation Note:
- Replace aluminium screw.

Remove feed line (3).





Seal feed line with matching plug from special tool kit 32 1 270 32 1 270 Plugs (Set).





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 12 14 Electronic Shift Units or Control Units.





Installation Note:
Clean contact surface of knock sensors on engine block.





Installation Note:
Pre-install feed line (3).

In so doing, tighten screw connection hand-tight only (it must still be possible to move the line at the holder).

Important!
Sequence of screw connection must be observed!

- Tighten nut (1). Tightening torque 13 53 6AZ 13 53 Fuel Injection Nozzles and Pipes.
- Tighten screw (2). Replace aluminium screw. Tightening torque 13 53 9AZ 13 53 Fuel Injection Nozzles and Pipes.





Note:
Add final details to vehicle.

Check stored fault messages.

Now clear the fault memory.