Crankshaft Position Sensor

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Thread: Crankshaft Position Sensor

  1. #1

    Crankshaft Position Sensor

    Hi all,

    following on from my previous 2 posts (Intermittant Starting Probs on 9-3 Aeor Coupe), I believe after doing lots of reasearch on this site that I am suffering from the Hot start Problem caused by a failing Crankshaft Position Sensor (although I am not experiencing any of the rough idling or stuttering issies others have reported).

    Can anyone confirm if the Engine cranks (turns over) with a faulty Crankshaft Position Sensor. My problems seem to rear their head when I take the car on a short journey (approx 1-2 miles), leave the car for 5 mins and then try to restart. The engine turns over fine but will not fire. Some posts have said that with a faulty Crankshaft Position Sensor, the Engine will not even turn over !

    I plan to change the Crankshaft Position Sensor anyway as it is a relatively cheap option. Any tips/tricks to make the change go smoothly. Will the new Crankshaft Position Sensor come with a new O-Ring or do you re-use the old one ?

    In addition, can anyone tell me how to test a Relay ? I want to check the fuel pump relay is not sticking as this was my 1st though as to why it wouldn't start.


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  3. #2
    Saab Newbie
    Join Date
    Jan 2012

    Re: Crankshaft Position Sensor

    Hi Crank sensor easy to change, no issues involved. keep ignition off and key out ignition, unplug cable from joiner then remove from engine block, bolt in new and reconnect cable and start the car. if fuel relay sticking you will hear the pump running on afte the engine is off

  4. #3

    Re: Crankshaft Position Sensor

    Its not that easy a job, a little bit fiddly to say the least. Recently changed mine (99 9-3 lpt) and ended up taking it out a few times as it did not resolve my problem and needed to recheck fit (eventually resolved with a new DIC).

    Firstly ensure you get the correct CPS there are two, identified with either a black or blue connector. Access is a bit tight and most people go in from underneath but I found the easiest was to unbolt the exhaust flange and move the exhaust to one side, only needs an inch or two to give enough access.

    Mine did not come with new o-ring or fibre washer but I believe most do, just make sure you take the old o-ring out before fitting the new one, obvious I know but some have been caught out by it.

    Fixing is by a single bolt, its a t-bit, I think mine was a t30 but this does seem to vary from t25 to t30, just make sure you have the right size and its fitted into the head correctly before applying any pressure, rounding off the head can lead to nightmares! You will also need a decent cranked driver with about a two inch extension to reach the head.

    All going well a couple of hours work but a bit chilly under the car at the moment

    All the best

  5. #4

    Re: Crankshaft Position Sensor

    I recently suffered a similar problem, HOT starting problems after short or long journeys.
    Engine would turn over but not catch and ignite.
    When it was cooling down the engine seemed closer to catching, but still didn't make it.
    When it was fully cool it started no problem.

    I was told it could be one of a number of things;
    Crankshaft Position Sensor
    DI casette
    Throttle body issues

    The problem was intermittent, and the one thing i tried to diagnose was to squirt cool water at the sensor when it was hot and not starting. (I know i know, i was warned about this, but I was stranded and it did work with no ill effects!)

    Being the cheapest option to start with I was going to change the Crankshaft Position Sensor myself as i was told it was an easy job.
    Sourced one, but after a couple of hours struggling with my face in the engine i took it down to my local garage who did the swap for £35.

    Since the sensor swap, no more starting issues hot or cold.

  6. #5

    Re: Crankshaft Position Sensor

    Hello Watch the rev needle while trying to start the car, if it doesn’t move it will be your CPS. If it twitches the CPS should be ok. I would change it anyway when approaching the 100k mark as it is likely to strand you in the middle of a junction at some point!! (I know this from brown underpant experience).It can be awkward to get to but remove manifold heat shield and bypass valve ridged pipe. A combination of uj's and extension bars will see you right. I did mine from above in roughly 40 mins.

  7. #6

    Re: Crankshaft Position Sensor

    Hi, im jumping here guys, ive got an 9-3 02 aero, and the engine light has just come on got 3 code 2 to do with di cassette and 1 for the Crankshaft sensor, like everyone else was wanting to go with cheapest option first, rang saab for the sensor and they said it was part of the cassette, now reading the posts that doesnt seem to be the case.

    So firstly where can i get the sensor from and has anybody got any guidance or pictures as to where it located.

    ps car has a very slight misfire but starts no bother and puts the power down no bother.


  8. #7

    Re: Crankshaft Position Sensor

    Hi All,

    thanks for the advice. I am peased to say I managed to change the Crankshaft Sensor (very tricky access) from above the car approx 4 months ago and not had any starting problems whatsoever since. Mine was held with a T30 Bit and I managaed to undo it with and adjustable head ratchet screwdriver. Result. Thanks for all the help and advice.

    On another note, I have also managed to fix my A/C Pixels which is also a bonus. I used the tip of a warm household Iron to re-connect the plastic ribbon to the contacts (not as hot as a soldering iron so less chance of melting the ribbon). Tried all the sticky pad options but these didn't work. I think the heat from the iron re-melts the original adhesive and gives a very good bond. 4 Months on and still 100% of pixels present

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