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Crankshaft Sensor Replacement
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Pelican Technical Article:

Crankshaft Sensor Replacement

Nick Czerula


3 hours3 hrs






Set of sockets, 5mm Allen bit, flathead screwdriver

Applicable Models:

BMW 323Ci Coupe/Conv (1999-00)
BMW 323i Sedan/Wagon (1999-00)
BMW 325Ci Coupe/Conv (2001-06)
BMW 325i/xi Sedan/Wagon (2001-06)

Parts Required:

Crankshaft position sensor, sealing o-ring

Hot Tip:

Work with a cool engine

Performance Gain:

Car will run well

Complementary Modification:

Replace your crankshaft

The crankshaft position sensor is used to synchronize the engine timing for fuel and ignition control. It is located near the starter motor, mounted in the engine block. The sensors read 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 your 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 BMW E46 crankshaft position sensor. You can access the sensor from below vehicle, working on the left side. The photos in this article show the throttle housing removed from vehicle for clarity, you do not have to remove it to replace your crankshaft sensor.

First raise and support the front of your vehicle safely.
Figure 1

First raise and support the front of your vehicle safely. Remove the lower engine plastic splash shield. The BMW crankshaft position sensor is located below the starter motor (yellow arrow) at left side of engine - disconnect the crankshaft sensor electrical connector by squeezing the release tab and pulling it away from the sensor (green arrow).

Next, using a 5mm Allen bit, remove the crankshaft sensor mounting fastener.
Figure 2

Next, using a 5mm Allen bit, remove the crankshaft sensor mounting fastener. There is not a lot of room, so I used a short 5mm Allen bit with a 1" extension on my 1/4 drive ratchet.

Once the Allen bolt is removed, pull the crankshaft sensor out of the engine block.
Figure 3

I like to keep things clean so use a rag to wipe the area around the crankshaft sensor then install your new BMW E46 sensor and sealing o-ring. Torque the sensor to engine block to factory specs. Reconnect the electrical connector and install the engine splash shield. Start the vehicle and allow it to idle for about 1 minute. Check that the crankshaft sensor area is free of oil leaks. If your check engine was on, now would be the time to clear any DME fault codes using a BMW compatible scan tool or a code reader. Follow the instructions accompanying your code reader or scanner.
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Comments and Suggestions:
Dave. Comments: Nick, thanks for your comments.
September 23, 2015
  Followup from the Pelican Staff: No problem. - Nick at Pelican Parts  
Dave Comments: Hello. I have an '04, 2ltr 318i Touring 118k miles. Recently the engine has started to cut out occasionally. Mostly the ignition light will flash on for a split second then off again and the engine will stutter for a second then all will be back to normal again but on 2 occasions the engine has stopped altogether. Once I turned the ignition off then back on again the engine has restarted straight away. At all other times the engine runs ok. I have read elsewhere that this is a sign of a bad crank position sensor and I would like your opinion on this please.
September 20, 2015
  Followup from the Pelican Staff: Sounds more like a power problem. To be sure, check the DME for fault codes. You may have a fault for either the crank sensor or power supply. - Nick at Pelican Parts  
keegan Comments: i have a e39 528i bmw that crank but wont start, theres fuel pressure at the injector there was spark at the spark plug plus i put in new plugs and battery is also new.the rpm meter dont move when i try to start it.does that mean the crank sensor and the cam sensor is gone? the crank and the cam sensor wire look if the crank sensor is bad would you still gets sparks at the spark plug?
September 12, 2015
  Followup from the Pelican Staff: If you have spark, the crank sensor is likely good. Do you have good compression and injector pulse? - Nick at Pelican Parts  
BKL070 Comments: 2001 3 xi. I removed the crank sensor in this vehicle. From what I could see going from underneath is not worth it or even possible. Remove the air box and intake duct boots. There is a small canister mine is black plastic about the size of a food can. Loosen the bolt that holds the canister. You may need to disconnect the vacuum lines on the can, then move the canister out of the way. The crank sensor is under the can.
Note:The canister and lines are, from what I can tell, just for the flaps in your tailpipe. When I did this I did not know. Mine is already disconnected at the muffler. The vac hoses at the canister are going bad. I was able to get it back together but now I am going back to plug the line at the engine.
August 28, 2015
  Followup from the Pelican Staff: Thanks for sharing your installation process and experience. These type of comments add so much to the Pelican tech community.
- Nick at Pelican Parts
Dennis R Comments: 230K '02 330ci. I've replaced fuel pump, filter, cleaned injectors and o-rings, replaced O2 sx, ign. coil, sp. plugs, and checked vacuum lines, replaced throttle boot, oil pr. regulator, and pcv. Still having P0300 code multiple misfires and random cylinder misfires. I can still start the engine but with unsteady idle and will die eventually. If my crankshaft sensor is faulty, will I still be able to start the car you mentioned, the engine will not start. Is it recommended to change both the crankshaft and the camshaft sensor? Thanks so much!
August 8, 2015
  Followup from the Pelican Staff: The engine will not start if the crank sensor is faulty all the time. If intermittent, it could start.

I would check compression. - Nick at Pelican Parts
Michael Comments: I am having a problem starting my 2000 328i, but only after driving a short distance. If I drive for a long distance and shut the car off it turns right back on no problem. After trying from a short distance, the car will eventually start after waiting a few minutes, but drives poorly and hesitates after that. My fuel pump is working and car runs great other than that. It only seems to do this when it is a little colder out, when it is warm no issues. Any ideas?
July 17, 2015
  Followup from the Pelican Staff: Cold start tends to be fuel issues. What is fuel pressure and volume? - Nick at Pelican Parts  
Tom Comments: Hello I have a BMW 325i it was driving fine all day then all of a sudden I'm a the traffic lights and the car failed to gain power and go past 2-3k revs then it would idle by itself then eventually stall then I would start the car same problem rumble failing to get past 3k revs then eventually stall I ran a diagnostic test came up crankshaft cylinder misfire fuel something sorry can't remember but today the car seems to have its power and drive normally after clearing the faults any idea what's going on it's really baffling me
July 2, 2015
  Followup from the Pelican Staff: Sounds like an engine misfire. I would check spark, fuel and compression on all cylinders. - Nick at Pelican Parts  
Costelo Comments: THANKS,great site,very, very informative
June 18, 2015
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
Costelo Comments: Hi , i want to replace my crankshaft sensor as a preventative maintenance. The current sensor is still 100% good.there are no codes and the car runs fine.
Will i need to reset the DME after i install the new sensor?
June 18, 2015
  Followup from the Pelican Staff: No, you should not have to. - Nick at Pelican Parts  
cmar Comments: hello nick, 2001 325i 200k miles, new wiring harness. the car just stopped running and will not start, engine turns over, will not run. I suspect spark failure as there was plenty of fuel smell when it crapped out. 5 cylinders with misfire codes and both o2 sensor codes and that's all my peak research reader will detect. completely puzzled. reading your tech guides i suspect the crank sensor, but will the throttle positioner sensor also play a role. Thank you for any help
April 1, 2015
  Followup from the Pelican Staff: Throttle position sensor should not cause a not start, it would set a fault code if it were faulty.

I can't help without knowing what is missing from the system when you are trying to start it. When your engine doesn’t start you’ll want to check the basics. Check spark, fuel injector pulse and fuel pressure, volume, quality and engine compression. Are there any fault codes? Once you figure out what is missing, it will be easier to diagnose.
- Nick at Pelican Parts
Willis car ever start again mcgee Comments: Thats what i thought. Here are some more clues to this no start mystery: When i push the start button the engine will continuously crank until i either let the clutch pedal out or push the start button to stop the cranking . Also i cant get any code reader to link to the vehicle. Not even a new matco scanner or even a snap on scanner. i think it was a solus??? anyways, i have bench tested every relay that i could find on the vehicle along with all of the fuses. I cant find a wiring schematic anywhere for this car. Its a 4 door 325i. The manufacture date is 06/2005.
February 7, 2015
  Followup from the Pelican Staff: The cranking scenario is normal, it will crank for a defined amount of time, until it start - or not.

if you can't communicate with the DME, I would this the issue may it. Check if the DME is receiving power and ground, good ignition power. Then check the data lines. If all is OK and the DME is not functioning, it may be faulty.- Nick at Pelican Parts
Willis mcgee Comments: F1 fuse is good. Is the dme relay supposed to power up when the ignition is turned on or does the ecu have to receive crankshaft position signal while cranking before it powers up the relay? Would a bad crankshaft position sensor prevent the dme relay from turning on?? Also what is the purpose of the resistor that is located on the cap for the obd2 port?
February 5, 2015
  Followup from the Pelican Staff: No, the crank sensor would not. The DME relay should be on when the key is in the run position. - Nick at Pelican Parts  
Willis mcgee Comments: Hello pelican i have a 2005 325i that cranks but wont fire. Now here is what i have found: no power to ignition coils while cranking, all fuses are good , plenty of fuel pressure, cant get code scanner to link to vehicle. Ebox fuses are all good. The relay that powers the coils is good.... Im stumped!
February 3, 2015
  Followup from the Pelican Staff: No power to the coils, power comes from the DME relay (located engine compartment e-box) Fuse F1 in the front e-box as well. Start there.- Nick at Pelican Parts  
Greg Comments: My son has a BMW 2001 330ci that started running poorly and dash lights came on. he checked the codes they said bad mass flow sensor and crankshaft sensor. He pulled the connections loose and cleaned them and plugged back in and cleared codes. It seemed to run better for a short time then bad again. He checked codes and it showed an intermittent bad crank pos. sensor again. He replaced the sensor and cleared codes he started it up and ran it for a bit and lights on dash where all on and car seem rough. He checked codes again and it showed fulltime bad crank pos. sensor again and it won't let him clear that code no other codes showing. It still driving poorly low power limp home mode and dash lights on. I read a few places DME and ECU need resetting but that's a shop or dealer thing. Any ideas about problem ?
January 26, 2015
  Followup from the Pelican Staff: I would check the signal from the crank sensor to the DME. You may have a damaged wiring harness. - Nick at Pelican Parts  
vance28 Comments: BMW 3251 1995 when i start it , and it warms up , a min .the timing seems to be off a little. anyThing electric radio, windows exccelerating the pedal,the idle seems to waver its t timing belt, or dcould it be a sensor
January 10, 2015
  Followup from the Pelican Staff: I would start by checking the charging system. Your issue may be low voltage. - Nick at Pelican Parts  
Val Comments: Would this procedure work for a 2004 330ci?
January 1, 2015
  Followup from the Pelican Staff: Yes. - Nick at Pelican Parts  
Sam Shows Comments: My BMW e46 M54 engine 2000 model has a bad take off as well as shutting down in traffic with dead slow speed or when stationery in traffic, however your explanation I conclude it could be the Crankshaft Sensor. Kindly advise before I buy a new sensor?
October 7, 2014
  Followup from the Pelican Staff: I have seem camshaft and crankshaft sensors cause this issue. I would start by checking the DME for fault codes. If the system is not working properly, a fault code will be set. This will be your best bet when diagnosing.
- Nick at Pelican Parts
Tamim Comments: Hi. I have a 2003 325i. Two days ago my passenger window was stuck when i lowered it all the way, took it to my mechanic. Today he told me the window motor is okay but he thinks the crankshaft sensor is bad since the car did not start. he powered the window from outside which worked.
Also, i have the following codes from the engine light:P2240 heated oxygen sensor bank 2, P2237 heated oxygen sensor bank 1, P0174 system too lean bank2, fuel pressure or volume.
can you help explain all this please?
September 4, 2014
  Followup from the Pelican Staff: The codes for the o2 sensors need to be dealt with first, then you can address the fuel trim fault if it is still present. CHeck oxygen sensor operation and replace as needed. Then clear the fault codes and see if the fuel trim fault returns. I do not see the correlation to a crank sensor. - Nick at Pelican Parts  
pauli Comments: The click to order parts takes you to a horn, not the sensor.
July 22, 2014
  Followup from the Pelican Staff: Thanks for catching the link error. I will have it fixed. - Nick at Pelican Parts  
emmanuel Comments: alright cool cool so should i remove the starter?
November 18, 2013
  Followup from the Pelican Staff: If you need the space, yes. - Nick at Pelican Parts  
emmanuel Comments: where are you located maybe i can bring the car to you, and what kind of vise grip, the bolt looks chipped out, also were can i get another bolt n would i brake around the senor
November 18, 2013
  Followup from the Pelican Staff:

Just a small vise grip, pretty standard. They come in all sizes. You can get a bolt from Pelican Parts, Give our parts specialists a call at 1-888-280-7799. They can help you find the right bolt.

If you remove some of the sensor mounting material you should be able to get a better grip.

If there is any hope for the Allen fastener, you can also try to hammer a larger sized Allen bit into the fastener. I always go one size bigger in a fractional sized bit. if you use this method, do not hammer hard on the crankcase. The bit should go in with light tapping. You don;t want to damage the engine.- Nick at Pelican Parts
emmanuel Comments: a vise grip is to big to fit in there remember this is a bmw 323i its in a very tight spot and i do not have a extra bolt to replace it
November 18, 2013
  Followup from the Pelican Staff: If the bolt is rusty, you are going to have to replace it. I have small vise grips that would fit in the space, so that is an option. If you need to make room, you can remove the starter. - Nick at Pelican Parts  
emmanuel Comments: i am trying to replace my sensor on my e 46 but the thing is the bolt is rusted and stripped also chipped out what cant i do ???
November 18, 2013
  Followup from the Pelican Staff: You can use vise grips to grab and remove the bolt. Or break the sensor away from the bolt, the plastic portion of it. Then use vise grips to grab the bolt. - Nick at Pelican Parts  

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Page last updated: Sun 11/29/2015 02:16:40 AM