Help with Stuck Crank Position Sensor

Has anyone experienced a stuck crank position sensor and if so, how did you finally remove it? The torx bolt unscrewed with no problem but I can’t get enough leverage to pull the sensor out. I’ve tried PB Blaster and I’m able to rotate it a bit with a spark plug socket but it just won’t loosen up enough to pull it out.

As I recall there is an o ring on it that gets stuck. You will probably need to break the black part off, extract the guts, and pry the cylinder out.

Update: Never could get it out despite a month of heating, oiling, drilling a concrete screw into it and prying, pulling with pliers...you name it. Finally had it towed to a Porsche specialist shop and it took them SEVEN HOURS to remove it in pieces, but they did get it out and replaced it with a new one. And then the car wouldn't start. It cranks but there's no oil pressure in any of the cylinders despite the car running great right up until I started trying to get the sensor out. Now they're taking the engine apart to see what went wrong but they think it's something catastrophic. I just can't imagine how though. Anyone ever have anything similar happen after their crank position sensor was replaced?

I'll take a wild guess and say the new CPS is not reading the crank, they should hook up to ECM and check if RPM are reading. another question is was the car running before changing the CPS.

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Yep, the car was running fantastic and has been trouble-free aside from taking a few seconds to start if the engine is hot. That�s what I was hoping the new CPS was going to fix. The car is driven around 70 miles per day as I commute to and from work and it doesn�t smoke or stutter at all. The car has 66,000 miles. I�d be so happy if that�s all it turns out to be! I�m already around $2,500 into what should�ve been a $70, thirty minute fix in my garage.

Difficult hot start can also be caused by corroded 'Y-cable' providing +12V to the starter. Search for it on rennlist.com But that's not your issue at the moment , since the engine is cold currently. What do you mean exactly by 'It cranks but there's no oil pressure in any of the cylinders'? No oil pressure indicated by the gauge on the cluster or truly no oil pressure being built when measured using an external gauge hooked up in place of the sensor on top of cilinder head/bank 2? Or do you mean no compression on any of the cilinders?

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The shop i took it to pulled all six plugs and tested each cylinder for oil pressure and they�re all low. They checked the timing chain and it was still in place and set. I going there in the morning to see photos they�ve taken of the cylinders and rings which are apparently coated in oil for some reason. I�ll know more tomorrow, but they�re talking about s $12k to $15k tear down to find the problem and I�m convinced it can�t be anything that serious because it was running great.

Does that include putting it back together, or will that cost another $12k-15k?

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Not sure where to even start if what you've explained is even half accurate...... 7 hours labor to take out a stuck CPS is ridiculous for a real professional skilled tech. Assume you mean cylinder compression is low, not oil pressure.? Even with low compression ( or even with zero comp on a cylinder or 2 or 3, ) engine should still start and maybe run ruff, but it should start up... My bet is, if you try to crank it over the tachometer needle will stay stationary with no 'bounce' showing no voltage from the CPS... Just do yourself a favor and get your car out of that shop, as no way you have all these numerous problems after bringing in an other wise ''great running car" that just needed a CPS installed. Not saying engine might not need a rebuild (most high mile m96 do), just that it should at the least start and run as good as it did before its $1000 CPS job...

I dont understand either. The cps is in the bellhousing so worst case u r droping the trans. Unless its a tip then u haved to drop the motor too. My guess is they have the cps plugged into the wrong sensor. There r 2 of the same plugs in exactly the same spot where the cps is. It is very common to get the backwards. Good luck, sounds like some diagnostic work instead of the parts cannon would have saved u a lot of headache.

I have had CPS no start issues with the sensor being .030 to far away from a crank or cam gear to trigger a reading, Who know what they did for 7 hours and damage they did to the sensor bore. I would definitely take the Porsche to a reputable shop

Quote: I have had CPS no start issues with the sensor being .030 to far away from a crank or cam gear to trigger a reading, Who know what they did for 7 hours and damage they did to the sensor bore. I would definitely take the Porsche to a reputable shop I'm really hoping it's something that simple! When your car didn't start, did it crank like normal or just make a spinning sound? Mine's just spinning. The shop removed the oil filter and looked for shrapnel and there wasn't any, and the IMS bearing timing chain tensioners, and timing chain have all been ruled out now. Bore scopes show no scoring on the cylinders but what may or may not be tiny cracks in the walls of cylinders 1 and 2 - they won't know unless the engine is disassembled at a cost between $12k and $15k. What give me hope that it's nothing so catastrophic is the fact the car ran and drove just fine right up until I jacked up the left rear tire and tried to remove the CPS. I was given the old sensor today (and my $2,400 bill!) and it had expanded just a bit right where it meets the bell housing. Not much, but just enough to not come out. Tomorrow the car is getting towed to another shop just to get a second opinion before I start shopping for a used 3.6L M96 manual motor like the shop advised. That's what the CPS looks like after over a month of prying, drilling, oiling, heating, and pulling on it. Ridiculous, but glad it's out of the car.

Quote: Does that include putting it back together, or will that cost another $12k-15k? That figure was for the diagnosis to see if the piston rings failed or the cylinder sleeves cracked somehow. They have to drop the motor and take it apart, but I'm getting a second opinion this week.

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Yes, I should've said cylinder pressure. I tried starting the car today at the shop and the tach needle is motionless while the engine makes a spinning sound rather than its usual cranking sound. The car/motor have 66k miles on them and it's driven five days a week or more. The shop is a very reputable one that's been servicing nothing but Porsches for over 30 years, and if the car had been running rough, smoking, burning oil, getting bad mileage, or not feeling perfect right up until I tried to get that sensor out I'd be more worried that I really do have the blown engine they think I do. The car is being towed to a different shop tomorrow to try and get a second opinion.

Is it possible that the replacement CPS is also bad? Have they tried another known working CPS (or test the CPS in your car right now in another 996)?

Super dupper simple test......crank the motor and tell us if the tach moves......

I want to see a video of the symptoms.

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No tachometer movement at all when trying to start the car. And I just caught a huge mistake I made that could well be the reason: I bought the wrong sensor from Pelican. The one I bought is for pre-2002 models and my car is a 2003. Just called the shop back and they're ordering the correct one that'll be here tomorrow. Still doesn't explain the lack of compression, but I did try to start the car several times with the wrong sensor and I may have washed the cylinder sleeves off with gas. I'm going to have the shop squirt some oil into each sparkplug hole to try to get a good oil seal for the rings when they go to start it up again. I'm feeling pretty confident this is gonna fix the problem.

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I should've filmed the stationary tach and the sound of just the starter spinning when I was at the shop today but I didn't think to. I think I may have figured out the issue though - I'll know if I'm right in a day or two! Sure hoping so.

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Not bad, but it's VERY possible I bought the wrong sensor when I ordered it off Pelican last month. Because that's just what I did. 2003 911 C2's use Bosch 986-606-112-04 and like an idiot I ordered a Bosch 026-121-02-04 for 2000-2002 C2's. The shop didn't catch my mistake when they installed it but they've ordered the correct one that'll be here tomorrow.

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This exactly! The connectors on the wiring loom are color coded. One light grey, the other black. You want the black plug on the CPS. Change those plugs around, if it doesn't start. For no other reason than to exclude it as the cause. There was a response by Porschetech3 a while ago to a thread that dealt with exactly this root cause. Do a search for it and take it from there .

Just checking that your engine has been disassembled and you're looking at 15K to fix because the wrong sensor was installed? The shop performing the initial work seems incompetent.

I'm a bit worried his starter is free running and not cranking the engine? Unless the rather hopeless shop forgot to put the spark plugs in. That tends to lower the compression.

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Let�s not toss the word �incompetent� around so carelessly. For one, the engine has yet to be disassembled.

Since u have no tach then its either the wrong one like u think or they have it pluged into the wrong connector....or both. The no compression thing sounds like a bad starter, maybe. Need ti hear it. I really doubt u have an internal engine issue. Did they remove the trans to extract the sensor?

I agree with that. The impression we get from the shop might also be due to some of their info is 'lost in relay' by the OP. E.g. Oil pressure in the cilinders, pictures of the piston rings,.. But he's in good hands here on rennlist and this will end without a15k bill and a running engine .

Question to avoid this... Do you use any stuff between CPS and block to avoid the sticking we have seen here? I'm installing a new CPS while doing much more with engine out service during winter.

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The issue is oxidation between the aluminum bellhousing and the sensor. A little bit of antisieze at the base if the sensor will deff help buy avoid the sensor tip.

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agree something might be good to use to prevent it from seizing in its bore. Even though I absolutely luv using/recommending anti seize on many things, it would not be my first choice. Don't like using copper or aluminum based never seize on plastic with electrical sensors. But sure it will help prevent seize ups and be fine.. My first choice would be a green marine grease used on o-ring and sides of sensor, not any on sensor tip . I'd even take off the oring and grease its groove liberally, same for the o-ring itself and the sensor sides. Keeping its tip clean grease free. I'd also lightly clean the sensor bore/hole with some crocus cloth, or even plumbers sand cloth rolled up on a deep socket to fit the hole. Lots of ways to do this, probably most any type thick lubricant will help. Probably most of these new CPS will be easy to remove for many years. As the ones we hear about getting stuck have been baked in for 25+years mostly... JMO

A little dap of super lube synthetic grease.

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They ended up getting it to come out with a combination of heating it and pulling at it for six hours at $200 per hour labor. I can't even imagine what it would've cost if they'd had to separate the bell housing.

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That I am - you guys are fantastic and I can't begin to tell you how much I love this forum! The 996 Owners group on FB is also pretty helpful, I'm finding. So, the conclusion of this little debacle was....an oil flooded engine that was keeping the crank from turning and making it appear there was no compression. That was all. When I had the car towed to a shop around the corner for a second opinion the mechanic called me two hours later to tell me it was fixed and running great. He spent one hour figuring out why only the starter was spinning but the engine not cranking, then another hour clearing the oil flooded cylinders. Total cost was $390 US and I've put 200 happy miles on the car since then. I plan to take the car back to the first shop as a teaching moment for the new owner and mechanic who misdiagnosed the problem. Imagine if I'd spent over $12k to drop and disassemble the motor?!? The $3,400 I ended up spending there was not a complete waste, as they got the old sensor out and now I know I have some bore scoring to deal with. Time to start saving up for an eventual engine rebuild or replacement but I'll be working to keep this motor on the road as long as possible.

Just reminds me why I do all my own work!

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Hopefully you've not described your problem above accurately,, that the 2nd shop 'fixed'. Hopefully there was some misunderstanding between you and them, as what you've now described above is hydrolock. A very bad engine killing condition. Especially if it was so bad engine wouldn't even turn over. I'm worried you've bent a rod as the starter motor is strong enough to do that in hydrolcock condition. Also, if it was "oil flooded engine" only way that happens is from a failed AOS. And once they fail thats it they don't self heal. A failed AOS will cause engine to hydrolock again very soon more than likely. And this time might be when its running at speed and you throw a rod totaling the engine. So, if it were me, I'd ask the shop again. Did they write down what they found and how they 'fixed it' on your invoice.? And not drive it another inch till I knew what actually was happening... A hydrolock by the starter might have only slightly bent a rod and or hammered a bearing. This type damage will surface down the road in rod/piston/bearing problems....Can not compress oil, something has to give. Again,,, Hoping there has been some type of misunderstanding here and the above did not happen... Sorry for the bad news but better you know and at the least get the AOS tested/fixed...

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That's interesting to know - he did describe it as "flooded" but didn't say it had been hydrolocked by the oil. All six cylinders were moving freely with the crank at the first shop when they scoped the bores and checked the timing chains and tensioners, which was another reason they were so perplexed. The repair receipt doesn't go into any detail but I'll ask him this Monday. If anything is bent or amiss it sure isn't affecting startup or performance, as the car is driving great these past 200 miles since I picked it up. There's no smoke at all and no weird sounds but I'll be alert for anything that comes up.

Don't bother if they don't write it down for you, since the relayed info onto here always raised more questions than were answered and that won't magically change. Just enjoy the car.

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So, not a good idea to at the least test the AOS ?, shop told him his engine would not turn over because "engine was flooded with oil". After the shop cleared out the oil engine did turn over and start. What else other than the AOS failing(failed) could possibly cause an engine to be flooded with oil bad enough to not let it spin over...?

The car was at a professional and is now driving fine again without it having cost 15k. Personally, I think OP is best off by not trying to relay any info between shop and rennlist, as he seems to not have the required technical competence to gain a benefit from it. Nothing wrong with that whatsoever.

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Not sure why you would say any of that. Asking the shop about where the oil could have come from, and why, is not questioning anyone's competence, by any stretch. It is very reasonable to ask if did they check one of the main sources of excess oil in our 996 engines. If the invoice didn't explain what happen and what they did to fix the issue (other than clean up the oil), I would want all the info I could get about exactly what was done and what the shop thought the likely cause was. I also wouldn't put any more miles on her until I could be sure the shop didn't miss anything. If it was the AOS (not saying it was) and it continues to fail and dump oil, then the OP may wind up spending a whole lot more than he just did. Better safe than sorry.

Oil flooded cylinders? Can you pull the oil cap off with the engine running or is it hard to remove? Better check the vacuum at the oil filler tube to eliminate a bad AOS or you may end up spending more than $15k, possibly a lot more.