C55 crank position sensor replacement
07-12-2021, 11:45 AM
#1
Junior Member
Thread Starter
C55 crank position sensor replacement
Hi all
Just completed this job, it's not for the faint hearted. While this has been covered in some videos and forum posts, I just thought I'd share some common lessons I picked up on the way which might help the next fellow in need.
Firstly, for the E8 bolt used on the crank position sensor (cps), use a 3/8 or 1/4 inch socket. I tried for about 3 hours to use a 1/2 inch socket and then eventually realised, when comparing it to the new sensor, that it was too thick to clear the tabs on the cps, even the 3/8 that I eventually bought was too thick near the top to give a perfectly straight and flush fit, but it did work eventually. A 1/4 inch drive is probably the best for this.
On the above note too, I had little success on getting the socket on until I removed the plug as this adds some thickness to the sensor thereby making the socket fit more off center, be mindful of this.
As for the method, I tried for hours to locate the socket while kneeling on the intake. Don't do it guys, I accidently kicked a small plastic clip broken off the front radiator bridge, not a big issue but given the choice, I'd still rather have the clip there.
I used the reach around with the left hand method, this means that your left hand goes behind the intake where the MAF sits. But given this, I could only get my thumb and index finger through the mess of pipes and harnesses there, its not very effective. For me, it was impossible to unplug the sensor this way.
Now onto what did work - I took the plastic cover off the injector harness but just a note on that, that harness will never be the same again once done (I'll post a seperate note on some help I need with that) but basically, there is no way to put the cable ties 100% back into position unless the harness is removed entirely (not something I wanted to do as well). And this cover is frail, some clips may break no matter how careful you are, just forewarning those that may want to do this. But it was necessary in my case as it was the only way my right hand would fit down there. But, once you get your right hand down the side of the head, you can grip the sensor harness plug quite nicely to take it off. There is supposed to be a small bracket bolted to the last bolt on the tappet cover holding a harness, this has to come off as well but mine is already missing probably due to some careless mechanic.
I also used a small ledLenser torch and balanced it on the edge of the head, right next to the tappet cover. You can actually see the sensor nicely with this and it will help you guide the socket onto the bolt. Please note that you should have your lanyard attached as the torch will probably fall, the lanyard saved me from having to fish it out more than once.
So, I stood next to the car (left hand side or passenger side, mine is a right hand drive so the steering wheel is on the correct side 😅 ), left hand down the back of the intake, looked from the top of the sensor with light shining from the torch and my right hand pushed the extension and socket down, grabbed it with my left thumb and index finger, and located it on the bolt. To build some sort of picture in your mind, practice or look at how the socket would fit on the new sensor, this made it easier for me. You basically have to guide it right up against the sensor to get onto the bolt, turn the extension slightly until it slips on. And when cracking it loose, try by all means to direct your leverage down the center of the extension and not by just turning the ratchet handle as it WILL slip off due to the awkward angle the whole thing is at. And then you will swear every dog and his mother. Once the bolt was almost out, I used my right hand to reach in there and take it out, you have almost full movement once you hand is in there and can pull the bolt up nicely. I also used my right hand to pull the old sensor up as it can be quite tight and I don't know how you'd do it with your left hand.
Next, re-fit - it's less of a nightmare. The new sensor was a tight fit so I used a plug socket attached to the extensions (note that the extension goes right down the side of the head, even for bolt removal, the pipes and harnesses are on the other side of it, closer to the firewall) and tapped it in with a rubber mallet, note TAP, not hit. I lined it up (using my right hand in there) just by eye, the plug hole is fairly square on top so you can use that as a guide. Next, use painters tape or similar to tape the bolt to the socket, it will break loose as soon as you achieve some torque on the bolt. Once in the hole, it was quite easy to screw it in. I think with the angle the extensions are at, it would be difficult to cross thread it as you can't apply much force, the bolt also has a taper front. Tighten that puppy up and you can start re-assembly.
Parts that came off:
Engine cover (both pieces)
MAF (keep this covered somewhere out of the way)
Injector harness plastic cover
Tools I used:
3/8 e8 socket with one Flexi joint, one full extension, and a half extension. I also bought a spring type flexible full extension but in all honesty, this wasn't absolutely necessary if the injector harness cover is off.
Small torch
Screwdriver (for prying clips etc during disassembly)
Plug socket
Rubber mallet
Consumables:
Cable ties x 5 (match size to ones that come off) and one large cable tie.
Sorry for the long post but hopefully this helps someone out.
P.S. make sure you put your hood into the service position before you start 🙂
Just completed this job, it's not for the faint hearted. While this has been covered in some videos and forum posts, I just thought I'd share some common lessons I picked up on the way which might help the next fellow in need.
Firstly, for the E8 bolt used on the crank position sensor (cps), use a 3/8 or 1/4 inch socket. I tried for about 3 hours to use a 1/2 inch socket and then eventually realised, when comparing it to the new sensor, that it was too thick to clear the tabs on the cps, even the 3/8 that I eventually bought was too thick near the top to give a perfectly straight and flush fit, but it did work eventually. A 1/4 inch drive is probably the best for this.
On the above note too, I had little success on getting the socket on until I removed the plug as this adds some thickness to the sensor thereby making the socket fit more off center, be mindful of this.
As for the method, I tried for hours to locate the socket while kneeling on the intake. Don't do it guys, I accidently kicked a small plastic clip broken off the front radiator bridge, not a big issue but given the choice, I'd still rather have the clip there.
I used the reach around with the left hand method, this means that your left hand goes behind the intake where the MAF sits. But given this, I could only get my thumb and index finger through the mess of pipes and harnesses there, its not very effective. For me, it was impossible to unplug the sensor this way.
Now onto what did work - I took the plastic cover off the injector harness but just a note on that, that harness will never be the same again once done (I'll post a seperate note on some help I need with that) but basically, there is no way to put the cable ties 100% back into position unless the harness is removed entirely (not something I wanted to do as well). And this cover is frail, some clips may break no matter how careful you are, just forewarning those that may want to do this. But it was necessary in my case as it was the only way my right hand would fit down there. But, once you get your right hand down the side of the head, you can grip the sensor harness plug quite nicely to take it off. There is supposed to be a small bracket bolted to the last bolt on the tappet cover holding a harness, this has to come off as well but mine is already missing probably due to some careless mechanic.
I also used a small ledLenser torch and balanced it on the edge of the head, right next to the tappet cover. You can actually see the sensor nicely with this and it will help you guide the socket onto the bolt. Please note that you should have your lanyard attached as the torch will probably fall, the lanyard saved me from having to fish it out more than once.
So, I stood next to the car (left hand side or passenger side, mine is a right hand drive so the steering wheel is on the correct side 😅 ), left hand down the back of the intake, looked from the top of the sensor with light shining from the torch and my right hand pushed the extension and socket down, grabbed it with my left thumb and index finger, and located it on the bolt. To build some sort of picture in your mind, practice or look at how the socket would fit on the new sensor, this made it easier for me. You basically have to guide it right up against the sensor to get onto the bolt, turn the extension slightly until it slips on. And when cracking it loose, try by all means to direct your leverage down the center of the extension and not by just turning the ratchet handle as it WILL slip off due to the awkward angle the whole thing is at. And then you will swear every dog and his mother. Once the bolt was almost out, I used my right hand to reach in there and take it out, you have almost full movement once you hand is in there and can pull the bolt up nicely. I also used my right hand to pull the old sensor up as it can be quite tight and I don't know how you'd do it with your left hand.
Next, re-fit - it's less of a nightmare. The new sensor was a tight fit so I used a plug socket attached to the extensions (note that the extension goes right down the side of the head, even for bolt removal, the pipes and harnesses are on the other side of it, closer to the firewall) and tapped it in with a rubber mallet, note TAP, not hit. I lined it up (using my right hand in there) just by eye, the plug hole is fairly square on top so you can use that as a guide. Next, use painters tape or similar to tape the bolt to the socket, it will break loose as soon as you achieve some torque on the bolt. Once in the hole, it was quite easy to screw it in. I think with the angle the extensions are at, it would be difficult to cross thread it as you can't apply much force, the bolt also has a taper front. Tighten that puppy up and you can start re-assembly.
Parts that came off:
Engine cover (both pieces)
MAF (keep this covered somewhere out of the way)
Injector harness plastic cover
Tools I used:
3/8 e8 socket with one Flexi joint, one full extension, and a half extension. I also bought a spring type flexible full extension but in all honesty, this wasn't absolutely necessary if the injector harness cover is off.
Small torch
Screwdriver (for prying clips etc during disassembly)
Plug socket
Rubber mallet
Consumables:
Cable ties x 5 (match size to ones that come off) and one large cable tie.
Sorry for the long post but hopefully this helps someone out.
P.S. make sure you put your hood into the service position before you start 🙂
Last edited by Sly1980; 07-12-2021 at 12:03 PM. Reason: Correction to clarity
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