Your fuel injection computer (DME) may output a code that indicates a faulty crankshaft position sensor (CPS). This important sensor tells the car’s computer where the flywheel is located in relation to the combustion cycle. The DME takes the signals from both the cam position sensor and crankshaft position sensor, and calculates when to fire the fuel injectors and spark plugs. If the crankshaft position sensor is not operating properly, your car will run very erratically or perhaps not at all.
Replacement of the sensor is not as easy as the camshaft sensor, unfortunately. The crankshaft sensor is located on the rear of the engine up against the firewall right above the starter motor. The reason for its location is so that it can detect movement of the flywheel as it spins. Based on the movement of the flywheel and also input signals from the various sensors on the engine, it provides the car’s electronic control unit with information required to trigger the ignition system at the correct time.
Begin by first disconnecting the battery at the access port on the front of the rear seat. Now open the hood and look along the rear of the right (driver’s side) of the engine. Locate the oil filter housing right behind the intake manifold. The crankshaft sensor is located next to the oil filter housing at the very bottom.
Squeeze the two tabs that hold the electrical connector to the top of the sensor. This is one of those things that may be easier to do from underneath the car due to the intake manifold being in the way or, you may be able to reach it with some very long pliers. Once released, pull the electrical connector up and off the sensor.
You’ll now need at least a 2’ extension in a ¼” drive with a swivel on the end and a 5mm hex bit to reach the sensor retaining bolt. It will take a bit of time to seat the bit inside the hex bolt. Just be patient and take your time. Once in place, loosen and remove the bolt. It helps to have a hex bit with a magnetic tip so you won’t drop the bolt into the bowels of the engine bay and find yourself very frustrated.
You’ll now need to pull the sensor out of the mounting bore. Once again, you may find this difficult as the sensor typically tends to stick in the bore as you pull it out. Again, a pair of long pliers and/or reaching the sensor from underneath may make it easier.
Once removed, place the new sensor in the mounting bore and carefully thread the retaining bolt into the mounting hole. Again, a magnetic hex bit really helps out here. Tighten the bolt down and reconnect both the electrical housing and then the battery.
Begin by opening the hood and looking down along the rear right side of the engine (green arrow). You probably won’t see the sensor without a very thorough search. It is located directly to the rear of the oil filter housing and above the starter.
Shown here is the crankshaft position sensor as it is located in the engine block directly above the starter. Squeeze the two tabs together (green arrows) to release the electrical connector and pull it off the top. It may be easier to remove the electrical connector from under the car. NOTE: in this picture, the intake manifold has been removed from the engine.
Shown here is the location of the sensor retaining bolt (green arrow). It is located facing the REAR of the car. Unfortunately, this is one of those instances, where you can’t get a camera in there to show the location.
Comments: If you look at my previous comments you'll see what I have written, but I will say again. Its been in at mercedes for 3 months. It scanned as cps fault, then they checked everythinkg external and said it all testd fine. I even got them to pull the gbox out to check the flywheel. And everything tested good. And they failed to give me a diagnosis!
March 4, 2014
Comments: sorry this is ryanp76 from down the page a bit. been away for a while
Mercedes sprinter 313 cd/dodge sprinter with a 2.2/2295L turbo diesel.. its a common rail diesel. merc has tested everything and it all aparrently tests fine. so they could not tell me what was wrong with it. such a pain as it drives perfect when running, just wont idle or start off the key. I can clutch start and keep the revs above 1500rpm, which seems to be getting worse now is 2000-2500rpm. yet merc diagnosed everything they could.
February 28, 2014
Followup from the Pelican Staff: If it won't start with the key, there is obviously an issue. I would check fuel pressure and operation of the fuel cut valve. Start by checking for fault codes and operation of fuel pressure using a Mercedes-Benz scan tool. - Nick at Pelican Parts
Comments: merc said low pressure was ok and don't have a compression tester and shouldn't merc have cheched compression and timing/ is it difficult?
February 26, 2014
Followup from the Pelican Staff: You didn't mention what type of vehicle you have. I don't understand what the statement. Checking timing and compression is not easy, but not impossible. - Nick at Pelican Parts
Comments: yes it is a diesel and haven't tried silicone spraybut ran an alternative fuelsupply to the filter to count the tank pick up out. can I bypass the fuelshut off supply?
February 26, 2014
Followup from the Pelican Staff: No, if you bypass it, the vehicle will not turn off. - Nick at Pelican Parts
MANNY THE ELECTRICIAN
Comments: HI , I HAVING TROUBLE WITH A 19909 M-B 300E , REPLACE THE CK SENSOR AT DRIVER SIDE REAR , ALSO THE IGNITION COIL AS LONG AS , SPARK PLUGS , WIRES CAP & ROTOR , THE THING IS THAT IT DOESNT HAVE PULSE AT ALL , NOTHING COMING FROM THE MODULE , AND IN THE SHOP THERES NOT A DECENT DIAGRAM FOR PIN POINT TEST ON THIS , PLEASE ANY HELP I'LL APRECIATE. THX
February 11, 2014
Followup from the Pelican Staff: Have you checked the injector pulse or fuel pressure?
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 pressure fuel, volume and quality. Are there any fault codes? Once you figure out what is missing, it will be easier to diagnose.
- Nick at Pelican Parts
Comments: I have searched the entire website on replacing the crankshaft position senor on my 1996 mercedez E320, the information you gave was by far the best on all sites. The only thing was I didn't follow your advice on using themagnetic hex bit to avoid frustration, I am frustrated, lost the bolt. If Possible advice on how to locate the bolt or if I can't will it cause problems.
January 6, 2014
Followup from the Pelican Staff: I would try to locate the bolt. If it fell into are area of interference, damage may occur. - Nick at Pelican Parts
Comments: After changing the headgasket of my merc c280 96 model the car wont start because there was no spark on the ignition coils and plugs. I managed to start it by shaking the wires leading to the crankshaft sensor. After running the engine and starting it several times now the car wont start and i have seen that there is no current on the wires leading to the crank shaft sensor.
December 3, 2013
Followup from the Pelican Staff: Sounds like the wires to that sensor are fried throughout. See how far you can trace them, looking for melted harness insulation. - Nick at Pelican Parts
Comments: i have a merc c280 1996 model and the car wont start after replacing the head gasket. i have checked and seen that there is no spark on the ignition coils and also the earth wiring cant be detected on these coils.
November 27, 2013
Followup from the Pelican Staff: Is there injector pulse?
Start by repairing the faulty ground you found.
Then test the crankshaft sensor. if the sensor is good, check engine compression. Engine timing may be off.
- Nick at Pelican Parts
Comments: I have a 1995 C280 and it wont start, the engine would crank but it wont start and theres no spark to going to the spark plugs
November 24, 2013
Followup from the Pelican Staff: Check and maybe try a crank sensor. - Kerry at Pelican Parts
Comments: It is a 2000 2.2 turbo diesel. First thing I tried was a can of start ya bastardaerostart and no fire. That sugestion is the best I've heard yet. And on startu and low revs they would be slapping around in timing! I thought they were a gear driven cam. No expert on this. As computerised diesels are new to me! I've stripped the front down already so might aswelldo the cam chain! What's the cost and eta for the chain? Merc had it for 3 months so its almost out of reg and I can't even drive it to the garage for inspection as is! Thank you very much for your reply! Its driving me mad, as I know someone out there has the answer! Good on you so far!
November 8, 2013
Followup from the Pelican Staff: Don't use starter fluid as you can blow up your airbox when you turn on the ignition key and the glow plugs ignite the starter fluid. Try silicone. A diesel should run on silicone. If not you have a basic compression problem. Highly doubtful. Does this have Bosch common-rail diesel electronic injection? What is the low fuel pressure reading and what is the high fuel pressure reading while cranking? Do you have a diesel compression gauge? - Kerry at Pelican Parts
Comments: I have a C280 1995 Elegance, I have changed the engine harness cable and had the ecu repaired. It has been of the road for a while starts fine but when you move the from P to Drive there is a juke as if its finding the gears. Is this a camshaft sensor issue? and how many sensor will I need to change?
October 25, 2013
Followup from the Pelican Staff: Doesn't sound like a cam sensor issue to me. What do you mean bya juke? Does it slam into gear when you engage the transmission? Is you idle speed too high? Is your transmission fluid low? Check these things first. - Kerry at Pelican Parts
Comments: ive got a mb 313cdi,its in at mercedes dealership as it one day decided it wouldnt drop below 1500rpm without stalling, and then wouldnt start off the key, i can clutch start it and it drives fine with full power as long as i keep it above 12-1500rpm. it read a crank sensor fault. so at mercedes dealership we replaced the crankand cam sensors, had the key chip tested, checked wiring, even took the box out to see if the flywheel lined up ok. and it still wont start off the key and reads crank sensor fault! so im up to about 10 hours labour with no diagnosis. and no joy! it has 630000km on it. but other that this is a great vehicle. any help out there?
October 21, 2013
Followup from the Pelican Staff: Do you lose spark and injector pulse under 1500rpm? Can you keep the car running on silicone spray while cranking it with the key. Your timing chain may be stretcehed out so the cam and crank sensoro out of sync. This is hard from me to know because I am in America and Mercedesn Benz did not see the 313cdi here. I assume this is a diesel and there is a shut off for the fuel. It's even harder to say because I don't know what year it is. - Kerry at Pelican Parts
Comments: My 1997 C280 MB would not start. The engine turns over. Note: The motor was warm. I waited couple of hours and started fine.I have never had any problems with this vehicle in ten years. Any ideas???
July 4, 2013
Followup from the Pelican Staff: Have you scanned for fault codes?
Comments: We were charged £689.16 to have a new crankshaft position sensor fitted to a 2005 C230 SE Auto Coupe Mercedes
Do you think this is a reasonable charge?
June 13, 2013
Followup from the Pelican Staff: Sorry, I can't answer this question.
Comments: my car is a vw golf 4. i cant reach the speed of 130km/h and sometimes the speed drops when im driving even when i accelerate it stays the same. i wonder what is the problem?
January 29, 2013
Followup from the Pelican Staff: I suggest you post this question on a VW forum roy@pelicanparts
Comments: To - whunter - You wonderful creature you! Thank you for saving me from the vultures who Lie! BTW might you know what controls the headrest and those headlight wipers please?
December 19, 2012
Followup from the Pelican Staff: Hello nicola
Thanks, glad to help.
You have an e-mail from me with answers, and a request for further data.
It is easier for me to help you with off topic diagnostic assistance by phone or e-mail.
Please include the vehicle year, model, and VIN# with your questions. email@example.com Have a great day. - whunter
Comments: i was told that on a 300CE Mercedes 1990 that the rear crank shaft sensor was the only sensor, meaning there was no front crank shaft sensor on this model. is this true? Secondly I was told that there were 2 different measurements on this model a 57 inch for $160 and a 63 inch for $300. Is this true?
December 14, 2012
Followup from the Pelican Staff: There are two sensors.
#1. The one on the front of the engine is for the Cruise control/Tachometer. #2. On the driver side rear is the crankshaft position sensor.
The only one communicating with the engine control computer is the crankshaft position sensor.
Crankshaft position sensor, has been superseded
Comments: Hi My Mercedes 240E Elegance 2001 Automatic. Drove for 20 min and then cut out and wouldnt start. After looking at everything the car started again and this morning wont start. The engine turns but wont kick in. What can the problem be any idea?
Comments: why did 1994 mercedes-benz E320 stop engine after engine run about 20 minutes and couldn't start or hard start again engine light on? i check fuel system like fuel filter, hoses,injectors ,pumps, regulator and even drivers and replace new fuel. i replace the S-plugs after try to run too many timesS-plugs are bad & vibration. it is possible problem about crank shaft sensor or do you have idea?
November 14, 2012
Followup from the Pelican Staff: At the least, I would need the diagnostic scan codes to answer this question. - whunter
Comments: I am searching for reason why my 1996 E320 engine crank—but not starting 2 times in 2 years. Searched and people said to replace camshaft + crankshaft sensor. Mine is automatic transmission, does it has crankshaft? No flywheel i guess....
November 7, 2012
Followup from the Pelican Staff: They are correct. The most common issues are a bad camshaft or crankshaft sensor. Your car has both sensors.
camshaft position sensor MB# 0041530028
crankshaft position sensor MB# 0031539628
Comments: was starting too do this job and tried to take off the oil filter housing to access the crank sensor but it seems impossible to get the two rear bolts out off oil filter housing
October 2, 2012
Followup from the Pelican Staff: Put the bolts back in the oil filter housing, there is no reason to remove it.
It is a single metric Allen or Torx, holding the sensor.
I use a 1/4 drive socket set with a 24 inch extension, and a swivel attached to the correct bit.
Total labor time 1 hour or less.
Check out some other sample projects from the book: