12 14 600 Removing/replacing knock sensors (N54, N54T, N53)

WARNING: This page is about a different car, the 2010 BMW 135i, 2009 BMW 135i, and 2008 BMW 135i. However, it is still accessible from the selected car via links, so may be relevant.

Special tools required:

13 5 281
13 5 282
32 1 270

See FUEL SYSTEM - SPECIAL TOOLS .

See STEERING AND WHEEL ALIGNMENT - SPECIAL TOOLS .

WARNING: Disconnect battery negative terminal (risk of fire due to short-circuiting on removal). See 61 20 900 DISCONNECTING AND CONNECTING BATTERY NEGATIVE LEAD .
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: 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:
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 . See 11 61 050 REMOVING AND INSTALLING INTAKE AIR MANIFOLD (N54, N54T) .

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.

Fig 1: Identifying Plug And Fuel Line

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

Fig 2: Sealing Fuel Lines Using Special Tools 13 5 281 And 13 5 282

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Slacken nut (1).

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

Release screw (2).

Installation:

Replace aluminum screw.

Remove feed line (3).

Fig 3: Identifying Nut, Screw And Feed Line

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Seal feed line with matching plug from special tool kit 32 1 270.

Fig 4: Sealing Feed Line Using Special Tool 32 1 270

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Unlock plug (1) and remove.

Fig 5: Identifying Plug

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

Installation:

Replace aluminum screws.
Tightening torque 12 14 1AZ, see 12 14 ELECTRONIC SHIFT UNITS OR CONTROL UNITS .

Fig 6: Identifying Knock Sensors With Mounting Screws

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Installation:

Clean contact surface of knock sensors on engine block.

Fig 7: Locating Contact Surface Of Knock Sensor

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Installation:

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, see 13 53 FUEL INJECTION NOZZLES AND PIPES .
Tighten screw (2). Replace aluminum screw. Tightening torque 13 53 9AZ, see 13 53 FUEL INJECTION NOZZLES AND PIPES .

Fig 8: Identifying Nut, Screw And Feed Line

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NOTE: Add final details to vehicle.
Check stored fault messages.
Now clear the fault memory.