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Pelican Technical Article:

Knock Sensor Replacement

Nick Czerula

Time:

4 hours4 hrs

Tab:

$300

Talent:

*****

Tools:

Set of sockets (10mm, 13mm), flathead screwdriver

Applicable Models:

R56 MINI Cooper Hatchback (2007-11)
R56 MINI Cooper S Hatchback (2007-11)

Parts Required:

Knock sensors, knock sensor fasteners, intake manifold gasket and related fasteners

Hot Tip:

Work with a cool engine

Performance Gain:

Remedy knock sensor fault codes

Complementary Modification:

Replace engine oil

Knock sensors are piezoelectric knock sensors. The knock sensor is constructed of a crystal that when pressure or vibrations are sensed, electricity is created. Via software and sensor design, this crystal can be used to monitor a gasoline engine for noise or knock. The software in the DME is programmed to the frequency of ignition knock or detonation to prevent erroneous readings, as the sensor will react and create voltage with mechanical noises as well.

R56 model engines utilize one sensor to monitor engine knock. The knock sensor is mounted to the engine block, below the intake manifold above the starter motor. The knock sensor usually fails, setting a check engine light and a knock sensor fault code. When a knock sensor fails, the ignition timing on your engine may be held in a retarded position until the fault is remedied, therefore reducing engine power and the chance of detonation. When replacing the sensor, MINI recommends replacing the fastener as well. In this tech article I will go over how to test and replace the engine knock sensor on your MINI R56.

To test the sensor, you will have to gain access to the sensor. Then you will backprobe the connector with the ignition ON. There are two wires at the connector. One is a ground. The other is a reference voltage used for circuit integrity. Here's the quick test. Use a DVOM. Connect the black lead to battery negative. Then connect the positive lead to the sensor wires. One wire should read close to 0 volts. This is the sensor ground. The reference voltage wire should read around 2.5 volts, for a good sensor. A bad sensor will either short the reference voltage to ground, or not pull it down to 2.5, therefore giving a reading of about 5 volts. Reassemble the engine and check the DME for fault codes.

Remember that your car may have been serviced before and had parts replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have so be prepared with different size sockets and wrenches.

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If you're working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Never work on your vehicle if you feel the task is beyond your ability.

Our vehicle may vary slightly from yours as models do change and evolve, as they grow older. If something seems different, let us know and share your info to help other users. Do you have questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.

Disconnect the negative (-) battery cable. See our tech article on battery connection notes.

Remove the intake manifold. See our tech article on intake manifold removing.

R56 models engine utilize one sensor to monitor engine knock.
Figure 1

R56 models engine utilize one sensor to monitor engine knock. The knock sensor (red arrow) is mounted to the engine block, below the intake manifold and between the coolant pipe (yellow arrow) and the starter motor (green arrow).

Now it's time to replace the knock sensor.
Figure 2

Now it's time to replace the knock sensor. Working at the knock sensor, release the tab (green arrow) on the electrical connector and slide it off the sensor (red arrow). Move the connector aside (inset). Note the position of the sensor at this time. When reinstalling there is minimal room to connect the electrical connector between the starter and the coolant pipe. Positioning has to be just right.

Then remove the 13mm knock sensor fastener (red arrows).
Figure 3

Then remove the 13mm knock sensor fastener (red arrows). Remove the knock sensor from your engine.

MINI recommends replacing the microencapsulated fastener.
Figure 4

MINI recommends replacing the microencapsulated fastener. If you need to reuse it, be sure to apply new red thread locker (red arrow).

Be sure the mounting surface (red arrow) is clean.
Figure 5

Be sure the mounting surface (red arrow) is clean. Then install the new knock sensors finger tight. Then torque the knock sensor fasteners. Reassemble the engine and check the DME for fault codes.

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Page last updated: Fri 12/2/2016 02:52:37 AM