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PSA - Car won't start - Crank Position Sensor


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My Boxster is a 2000S with 64K miles. Over the past month or two occasionally the car would not fire. I'd wait a few minutes and then it would fire up. When it did not fire it turned over just fine but I would get nothing in the way of mis-firing or sputtering. I hooked up my Durametric and had a fault in the crank position sensor (code P0336 I believe). I removed the sensor and found a glob of goo right in the center of the tip. I cleaned it up and put a little contact cleaner in the plug connection and reinstalled. I also cleared the fault. For the past few weeks the car's starting has been faultless. Hope this info helps someone.
That is interesting information.

Any idea how a glob of goo would get on the sensor?
I imagine just wear and tear and it's near the clutch (I believe). The glob was not much bigger than a round pin head. I myself would hate to pay to replace that sensor when a quick wipe with a towel and it's good to go again. It is a bit of a chore to get at the sensor. Mark
Thanks Mark. It is good to know that it could be a "relatively" easy / inexpensive repair if you know what to look for.

We had the Crank Position Sensor cause stalling on our BMW while we were on a trip. It wasn't cheap to have it replaced at the dealer.
I don't thing the goo was the issue.
That part is a proximity sensor and should work fine even when covered in goo.
It probably had a loose or corroded connection so when you disconnected it, cleaned it and and reconnected it that's when you fixed it.
Happy Boxstering,
Pedro

Pedro Bonilla 1998 Boxster 986 - 280,000+ miles: http://www.PedrosGarage.com
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)

Racecar spelled backwards is Racecar
"Racing is life. Anything before or after is just waiting" ... Steve McQueen as Michael Delaney in "LeMans"
"If you wait, all that happens is that you get older"... Mario Andretti
"Being second is to be the first of the ones who lose" ... Ayrton Senna
I think the goo had a metallic component. The sensor is cylindrical with a flat circular surface on top. It is about 10mm across and I think the active area is about 2mm and in dead center. The blackish goo was a "ball" on only the center 2mm area only, the rest of the sensor was bright shiny and clean. However, I always use a contact cleaner on electrical connections, especially when I first unplug them. I do not like doing something twice so I take my time and do a little extra. My 2000 Box. S is a summer only car. The undercarriage has absolutely no corrosion.
I am experiencing similar symptoms as MarknearChicago in my 2007S Boxster with 36K miles. Always starts fine when cold. But when road temperature hot and after being off for 5 to 10 minutes the engine will crank, will fire what seems to be once or twice but then cuts off. After 3 or 4 attempts like this the engine starts up and runs fine with no issues. Could this be a crank position sensor problem? Are there two of these sensors, which is implied on Pelican Parts, one on each side of the engine. And if so, where are they located? On Pelican Parts the Bosch (OEM) sensor is $30.00 while the Porsche part is $200.00 plus so if DIY big savings on parts alone as opposed to dealer fix. Any suggestions/info will be greatly appreciated.
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oldhoo07s
I am experiencing similar symptoms as MarknearChicago in my 2007S Boxster with 36K miles. Always starts fine when cold. But when road temperature hot and after being off for 5 to 10 minutes the engine will crank, will fire what seems to be once or twice but then cuts off. After 3 or 4 attempts like this the engine starts up and runs fine with no issues. Could this be a crank position sensor problem? Are there two of these sensors, which is implied on Pelican Parts, one on each side of the engine. And if so, where are they located? On Pelican Parts the Bosch (OEM) sensor is $30.00 while the Porsche part is $200.00 plus so if DIY big savings on parts alone as opposed to dealer fix. Any suggestions/info will be greatly appreciated.

There is only one crankshaft position sensor. There are two camshaft position sensors.

The CEL is dark I take it?

Have you checked for any pending error codes?

The symptoms -- especially with the engine trying to fire then cuttng out -- doesn't follow form regarding a crankshaft position sensor.

One possible clue the sensor is the culprit is to observe the tach when cranking engine and it is manifesting this behavior. If the tach needle doesn't come up off the resting pin that could be a sign the crankshaft position sensor is not operating. On this note one might with an OBD2 code reader/data viewer monitoring RPMs in real time observe an absence of RPMs while the engine is cranking. I don't think I've ever bothered to observe this. Maybe I'll do this today.

If a replacement crankshaft position sensor is deemed necessary Pelican has offers these in prices from $97 to $272. See link below. Don't know what besides the differences in prices there are. Not all "OEM" sensors (and other components) are the same as what comes across the parts counter at the Porsche dealer.

[www.autoatlanta.com]

IIRC a Porsche tech can with a proper Porsche diagnostic computer can query for a crankshaft position sensor error. This is not a standard OBD2 error so off the shelf OBD2 tools are useless. Durameteric might also have this ability but I've never used that tool.

Before you replace anything if you want to try something with the engine cold and probably (but always safely) in the air find the crankshaft position sensor and first verify it is not loose. Carefully disconnect it from the wiring harness connector then carefully reconnect it. This will remove any surface corrosion and if this is the cause of the behavior eliminate it. Be sure you get the connectors together again right. I have never messed with the crankshaft position sensor but with other sensors: MAF, O2; they all have clips/latches that must be released to separate the connector halves then operated again to allow the connector halves to come together completely then the latch/catch released and confirmed it has locked the sensor halves together. Otherwise they can work loose over time.
Marc, thanks for your input. There is no CEL. I have not checked for error codes - I will check this weekend when I will have opportunity to do so, I have a Durameteric (not pro). I will also check the sensor to see if there are any loose connections. But I ask that anyone who can, please add to my limited knowledge as how to best access the sensor with no lift - passenger side, remove rear wheel, straight in at approx. 2 o'clock, on side of engine. Thanks in advance.
Replaced the Crank Position Sensor and the problem was resolved. It can be accessed via the passenger (right) side wheel well. I wish I had purchased the bolt too because the old one was in terrible shape.

[www.autohausaz.com]

[www.autohausaz.com]
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oldhoo07s
Marc, thanks for your input. There is no CEL. I have not checked for error codes - I will check this weekend when I will have opportunity to do so, I have a Durameteric (not pro). I will also check the sensor to see if there are any loose connections. But I ask that anyone who can, please add to my limited knowledge as how to best access the sensor with no lift - passenger side, remove rear wheel, straight in at approx. 2 o'clock, on side of engine. Thanks in advance.

Upon engine crank this AM the Boxster dash tech needle rose a bit off the pin as the starter spun the engine. The RPM reading on the OBD2 tool showed some RPMs too as soon as the starter spun the engine. 'course, the engine started rather promptly, as is its custom, but I believe the crankshaft position sensor was working even before the engine was running for I believe it is the crankshaft position sensor signal from which RPMs are derived.

I have no experience accessing the crankshaft position sensor. A number of Boxster owners have though and some have posted their experiences. This should tell you something about the job: Small hands is mentioned as a plus.

The sensor is apparently accessed from below. The sensor's electrical connection is accessed from above. 'course, the engine compartment will have to be exposed. It is right next to the AOS. The sensor is under the AOS.
Thanks Boxsterra and Marc. Last night I checked for fault codes with the Durametric and there were no fault codes. I raised the car, removed the wheel and located the sensor and found that both connections seemed to be tight. I did not loosen the connections and clean because of limited access from below on the electrical connection. Anyway, I have ordered a new sensor but am a little concerned about being able to remove & replace it because of tight quarters and the maze of stuff to go around. Boxsterra, since you have done this R&R, can you give some advice or tips on getting this done? Did you also remove the engine cover to get access from above? Any tips from anyone will be very useful.
... you can do it entirely from the passenger side rear wheelwell.
Get a good bright lamp in there so you can see what you're doing.
The most difficult part will be disconnecting the sensor. It's easier to move whatever other connectors are in front, so you have better access.
Once disconnected, use a loooong extension (36 in) to remove the bolt (allen) from outside the wheelwell.
It's also good to have a magnet on a telescoping rod so you can retrieve the bolt.
With the bolt out, pull the sensor straight out.
Replace in inverse order.
Happy Boxstering,
Pedro

Pedro Bonilla 1998 Boxster 986 - 280,000+ miles: http://www.PedrosGarage.com
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)

Racecar spelled backwards is Racecar
"Racing is life. Anything before or after is just waiting" ... Steve McQueen as Michael Delaney in "LeMans"
"If you wait, all that happens is that you get older"... Mario Andretti
"Being second is to be the first of the ones who lose" ... Ayrton Senna
What he said
Boxsterra - 1 month ago
I would add that with a car that old, it's possible that the bolt is seized. I would start by soaking it with PB Blaster and if it is hard enough to turn use a torch to heat it up. If you force it and break the bolt, it will take 10x as long to fix the mess (though it's totally doable).
Thanks Pedro and Boxsterra. I have ordered the sensor and a new bolt online (OEM Bosch p/n 0261210248 which is the exact same description of the sensor on the car, price of $30.50, while the Genuine Porsche part is $200.00 plus - go figure) and it should come early next week and I'll give it a go. Boxsterra, I have had the car for 10 years and still think it is new, at least not old (as I "think" of myself).
This past weekend I used the Durametric to check again for fault codes and found none. Waiting for the replacement sensor, I drove the car numerous times to try and replicate the difficult start when hot. Did not happen once. Not going to try and fix it if it ain't broke and will continue to drive.
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