Vectra crank sensor

Discussion in 'Vectra' started by Bob Smith, May 8, 2004.

  1. Bob Smith

    Bob Smith Guest

    Thanks to all who helped me find the diagnostic socket.

    I got me flash code. Trust me to have the 4 digit ECU, each starting with 0
    (10 flashes), yawn... anyway, the error code it flashed repeatedly was
    "crank sensor"

    1) On a Vectra 2.0 16v R reg with AC, how easy is it so change the crank
    sensor? Is it easy to find, and to get to?

    2) Is it the RPM sensor? cos the traction control light was lighting up as
    well. And it takes about a minute to get it started. It seems to have
    trouble starting when it doesn'n know the crank speed. Carbs used to do
    just fine. Isn't technology brilliant?

    3) Any tips on getting it started easily for a few days until I can get the
    bits or get to the garage?

    Bob Smith, May 8, 2004
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  2. Bob Smith

    malcolm Guest

    The reason for the difficulty in starting is because it is defaulting to the
    camshaft position sensor. There is no easy fix,however a small 8m ring
    spanner will undo the securing torx bolt. There is no need for a major strip
    down, but access isn't easy. The sensor is located behind the power steering
    pump, and can be accessed from the top of the engine, with a bit of a
    The wire to the existing sensor will need to be cut, and the new sensor wire
    will have to be rerouted, unless you wish to remove the pump.
    Replacing the sensor usually takes me about 20-minutes.
    malcolm, May 8, 2004
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  3. Bob Smith

    Bob Smith Guest

    Any idea how much they cost? Or how much a garage will charge me?

    I would do it myself if it is as easy as you say, but won't have time until
    next weekend.

    I was thinking of taking it to a garage monday morning, and want to know if
    they try and rip me off. I don't really want to leave it a week, since
    every time I start it I pour petrol into the cat, and risk flattening or
    destroying the battery.

    Bob Smith, May 8, 2004
  4. Bob Smith

    mike Guest


    mike, May 8, 2004
  5. Bob Smith

    Bob Smith Guest

    Thanks for the link.

    Is the "crank sensor" the same as "Sensor - Crankshaft Speed"? I can't find
    another sensor, so I assume it is the same thing.

    Just wondering why the ECU needs a crankshaft speed and a camshaft revs
    sensor? Does the camshaft not go at 2x the speed of the crankshaft?

    Bob Smith, May 9, 2004
  6. Bob Smith

    mike Guest

    well lets put it this way
    if it don't work, the ecu will disable everything. the car will not run.
    common fault, hence all the links & msgs about them.
    i'd go for changing it.

    mike, May 9, 2004
  7. Bob Smith said:
    It's so you can still get home with a broken cam belt. Bloody good

    Simon Atkinson, May 9, 2004
  8. Bob Smith

    Duncan Wood Guest

    Duncan Wood, May 9, 2004
  9. Replacing the crank sensor on a Vectra 1.8/2.0 with AC is easier than one
    without - the plug will fit through the gap between the engine block and
    pump mounting bracket.

    There is a reason for the cable being routed behind the pump bracket - if
    its replacement is 'bodged' and the wire routed in front of the bracket, it
    is not shielded from the heat from the exhaust manifold. This can lead to
    failure in quite a short time. Doesn't take much longer to do the job
    properly - not as long as having to do it again anyway.

    Remove eight from email to reply.
    Anthony Britt, May 9, 2004
  10. It was somewhere around Barstow, on the edge of the desert, when the
    drugs began to take hold. I remember "Simon Atkinson
    I thought there was an emergency pedal driven cable drive in the
    passenger's footwell to drive the camshaft in the event of a belt
    Grimly Curmudgeon, May 9, 2004
  11. Grimly Curmudgeon said:
    There is, but if you don't have a passenger...
    Simon Atkinson, May 9, 2004
  12. Bob Smith

    AM200 Guest


    It's a shame that most of the prices are missing and I have to email about
    every single item I want, then wait. It's easier to go to a local main
    dealer. At least the part is genuine and guaranteed.
    AM200, May 9, 2004
  13. Bob Smith

    malcolm Guest

    The same sensor is often known by different names.
    The camshaft position sensor's main function is to control the sequential
    fuel injection more precisely. If the cam sensor fails, the system will
    default to mpi and limit the revs to approx. 3500pm.
    malcolm, May 10, 2004
  14. Bob Smith

    malcolm Guest

    I disagree. Rerouting isn't a bodge. There is more airflow for cooling the
    wire, at the right side of the pump than there is encased in the pump. Of
    the many sensors I've replaced, the life of the sensor has not been reduced,
    if anything, it has been extended. Vauxhall, like othe car manufacturers,
    have had design flaws in the past, and I would argue that the existing wire
    routing is one of them. If I had my way, it would be modified on newer
    versions to run from a flywheel pickup, which have proved to have a far
    greater life on other vehicles.
    malcolm, May 10, 2004
  15. And where does the air flow past to get to the cable? Past the exhaust,
    picking up heat from the manifold on its way past. The pump bracket shields
    the sensor and wiring from heat radiated from the back of the manifold which
    is not protected by the heat shield. I have seen countless sensor wires
    routed in this way, and all have shown signs of overheating (shiny surface
    to the insulation of the wire or convoluted tubing). Some had even melted
    completely, allowing the inner conductors to short to each other. I think
    that the reliability of the sensor is down to the component itself, rather
    than its location on the engine or its wiring routing. Motronic systems
    have a crank sensor mounted in the same position behind the PAS pump
    bracket; the incidence of failure of these sensors is very low IME. I have
    only had to replace two of these AFAIR, both due to the cable being
    displaced and rubbing through on the multi-V belt.

    What do you feel is the problem with the exisiting wiring routing?

    Remove eight from email to reply.
    Anthony Britt, May 10, 2004
  16. Failure of either crank or cam sensor will invoke limp home mode and limit
    engine revs to 4500rpm.

    Remove eight from email to reply.
    Anthony Britt, May 10, 2004
  17. Bob Smith

    malcolm Guest

    We will have to agree to disagree.
    I have seen a number of sensor wires which have been chaffed, because of
    their location. To the right of the pump, there is continuous airflow,
    rather than the swirl which you would find behind the pump. Use an air temp
    pyrometer, and you will see the results for yourself. Behind the pump, the
    ambient temperature averages around 80C, whilst the new route seldom rises
    above 40C.
    I am convinced that the failure of the cks is often heat related.
    We are currently experimenting with a vaned air deflector which should
    assist in prolonging the life of the sensor, this is, however, still in the
    early stages. There are 12 vectras with this mod fitted, but they have only
    been installed for 6-months. To date, none of the Vectras have suffered
    sensor failure...This is still early days. If this does prove successful, we
    will be working on a system to cool the cps.
    malcolm, May 10, 2004
  18. Bob Smith

    Guest Guest

    To add that you should solder and heat shrink the conductors on the new cam
    sensor when you install it- choc block is NOT acceptable.

    Also before you start anything, pull off the cam belt cover and check the
    belt tension. These ECU's work on a very tight tolerance window and will
    light the MIL if the belt is flapping and consequently the cam timing is
    wondering about with reference to the crank. Usually they light the lamp the
    instant you go into overrun conditions if it is slack, but check it all the
    same what with the ecotec's propensity for belt snappage when the wind blows
    north east and you have black socks on.....(change the belt & tensioners at
    36k intervals !!!!)

    Guest, May 11, 2004
  19. Bob Smith

    Kog Guest

    Crank sensor (CKP) identifies engine speed and where TDC is.
    Cam sensor (CMP) identifies when No1 cylinder is on TDC.

    Used to change the engine fuelling mode from non sequential injection to
    sequential. IE Sequentially the injectors fire the same as the ignition
    firing order (1342). Non sequentially the injectors fire in pairs. 1&4 2&3.
    So it important to know when No1 is firing (as 1&4 come to TDC together)
    hence the Cam sensor.

    The system can run if either one fails, but goes into limp home mode, revs
    will be limited.

    Kog, May 12, 2004
  20. Bob Smith

    Bob Smith Guest

    Thanks for that.

    When the crank sensor failed, it took about 5-10 tries to get the engine
    started. It seemed to run OK, accelerating fine and ticking over evenly.
    Revs were limited to about 4500.

    Bob Smith, May 12, 2004
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