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N52 Engine Crankshaft Sensor Replacement
 
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Pelican Technical Article:

N52 Engine Crankshaft Sensor Replacement

Nick Czerula

Time:

3 hours3 hrs

Tab:

$130

Talent:

*****

Tools:

Set of sockets, 5mm Allen bit, flathead screwdriver

Applicable Models:

BMW X3 Sport Utility (2007-10)

Parts Required:

Crankshaft position sensor, sealing O-ring, crankshaft sensor fastener

Hot Tip:

Work with a cool engine.

Performance Gain:

Car will start and run well.

Complementary Modification:

Repair oil leak from faulty crankshaft sensor sealing O-ring.

The digital motor electronics (DME) engine management systems in BMW E83 X3 vehicles with an N52 engine uses the engine control module (ECM) to control fuel injection, ignition and other important drivetrain functions. The ECM sequentially triggers the fuel injectors to spray fuel into the intake ports and then, a split-second later, triggers the ignition coils to fire the spark plugs. This sequence of events is timed by using the crankshaft position. Using the signal from the crankshaft sensor, the ECM "knows" which cylinder is ready for fuel intake and then, later, for ignition.

The crankshaft position sensor is located near the starter motor, mounted in the engine block. The sensor reads a toothed reluctor wheel mounted to the end of the crankshaft. It then sends a signal to the DME used to identify cylinder location. If this signal is missing, for example from a faulty crankshaft sensor, then the engine will not start. You can consider the signal from the crankshaft sensor the RPM signal for the DME.

In this article, I'll go over the steps involved with replacing the crankshaft position sensor. Access from below is difficult due to the front driveshaft and tight fit of the suspension and engine. I suggest removing the throttle housing and replacing it from above.

Keep in mind that when your car was serviced before, parts may have been 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 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. Do not work on your vehicle if you feel the task is beyond your ability.

Vehicle models change and evolve as they grow older, so the vehicle shown in our illustrations may vary slightly from yours. If something seems different, let us know and share your info to help other users. Questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.

Remove the throttle body. See our tech article on throttle body removing for N52 engines in BMW X3 models. The starter motor is shown removed for clarity in the article.

The crankshaft position sensor (red arrow) is located near the starter motor (blue arrow), mounted in the engine block.
Figure 1

The crankshaft position sensor (red arrow) is located near the starter motor (blue arrow), mounted in the engine block.

Working below starter motor at left side of engine, disconnect crankshaft sensor electrical connector (green arrow).
Figure 2

Working below starter motor at left side of engine, disconnect crankshaft sensor electrical connector (green arrow).

Next remove crankshaft sensor E8 mounting fastener (green arrow).
Figure 3

Next remove crankshaft sensor E8 mounting fastener (green arrow). There is not a lot of room, so I use an extension with a swivel attached to the E8 socket on my 1/4 drive ratchet. Once fastener is removed, throw it away, it has to be replaced.

Once fastener is removed, pull crankshaft out of engine block.
Figure 4

Once fastener is removed, pull crankshaft out of engine block. Be sure sealing O-ring comes out with sensor. If it stays in the block, retrieve it with a small pick. If sensor gives you trouble coming out, gently lever between sensor retaining bracket and engine block. Be very careful not to damage engine block. Install new sensor and sealing O-ring. Tighten sensor. Reconnect electrical connector and install engine splash shield. Start vehicle and allow to idle for about 1 minute. Check that crankshaft sensor area is free of oil leaks. If your check engine was on, now is the time to clear any fault codes and you are done.

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Page last updated: Tue 8/15/2017 03:24:49 AM