CPS failure with no warning

[mikeloadsasaabs]

Had the misfortune today to break down on one of the busiest roads in Salzburg at one of the busiest times  . SWMBO and I were crawling through through the traffic and the engine just cut out, with no chance of restarting. Rang the motoring club, who took 90 minutes to arrive. After plugging it into his OBD reader, he pronounced the CPS as "kaput". So we then had to wait to be recovered, and eventually got home 4 hours after breaking down.

Anyway, a couple of questions for the assembled multitude:

• presumably he pulled a code - I don't know what it was, but I'll put my own reader on in the morning to check. The question is, can that fault code indicate any other fault, or is it definitely the CPS?
• does anyone have the Saab part number for the CPS, and is it available from a GM dealer? Is it best to fit a Saab original part rather than aftermarket? 2004MY Aero.

Lastly, is it easy to replace, and is there anything special to look out for apart from making sure the O-ring for the old one is taken out before fitting the new sensor?

[sgould]

Article : Crankshaft position sensor
PartNo : 55557326
Usage : 2006-2010
Order Quantity : 1

You need a very short Torx driver There isn't a lot of room.  You also need a cold exhaust pipe.

I'm surprised a CPS stopped the car and wouldn't let it start again, but I suppose an open circuit on a broken wire would do it.

You can check the resistance of the CPS.  The connector is the blue one (on mine) in the block of three under the big inlet pipe behind the engine beside the throttle body.  Three pins.  Only two show a reading across them.  It should be between 770 ohms and 950 ohms.

[mikeloadsasaabs]

No chance of the exhaust pipe being other than cold, I have a dead car on the drive   

Is the part number the same for the 2004MY?

Thanks for the tip re the Torx driver. I've looked at a couple of "how to" videos on YouTube, the only real problem  seems to be how much WD40 I'll need to loosen the screw! Luckily I don't need the car for a few days.

[Audax]

Is the part number the same for the 2004MY?

That part is the same for all years of the 9-5, I'm sure we had a conversation recently where I said yours must be ready to die soon!  However there is a possibility that it's a wiring or ECU fault but that is very very unlikely.

Personally I would go for a genuine Saab part or Bosch as the Saab part is Bosch, expect to pay £60-£80. I have known problems from cheap ones and I just don't think it's worth it even on an older car to save the money although people have reported success with some of the newer non-genuine crank sensors. However to my mind £60 to avoid the potential problems is worth it as at most you'll save maybe £40.

I've never had a problem replacing a CPS and I don't think I've ever taken more than 10-15 minutes to swap one (as long as the car is cold!) the way I approach the job was always from underneath the car using a short ratchet with the right torx bit in it. I have seen many people struggle though as if that approach doesn't work with the tools you have then try another.

[mikeloadsasaabs]

Thanks Audax. I have just pulled the code with my Vgate scanner and it very helpfully says "P0337 Crankshaft Position Sensor A circuit low". Checked the resistance, and am having difficulty making sense of the readings as shown on my analogue meter, the calibrations are a bit strange. It reads "20" whether I have the range set to X1 ohms or X1K ohms  .

Is the code definitive - i.e. should I rush out and buy a new CPS (yes, yes, I know it won't do any harm!) but I am stuck without a car in the wilds of Austria    and I need to be fairly sure it will fix the problem.

I was erring on the side of buying the genuine article anyway, I heard on one of the videos I listened to that non-Saab parts don't always last very long.

[sgould]

When you turn on the ignition, does the fuel pump run?  I had a sudden failure on my 2002 saloon and that was found to be a broken wire in the fuel pump feed. You should hear it run for a second or two under the back seat.  It will stop pumping as soon as the fuel pressure is reached.  It won't start running again until the pressure drops when the engine starts. If you listen to the pump too soon, the pressure won't have decayed and the pump will only run for an instant.

Mine failed as I set out from the traffic lights across the A4 in Brentford. I stopped, straddling all three lanes of the A4 in the evening rush hour. 

[sgould]

When you are checking the resistance, are you checking between the pins on the connector, or are you checking the pins to earth?  The reading is across two pins, not to earth.  Only one pair should show a reading and that should be in range.  If its not, the CPS has gone. 

[mikeloadsasaabs]

Checking the pins on the cable to the CPS.

Am awaiting a callback from the dealer re parts availability. Irrespective of whether it's the problem, it seems daft not to fit a new one at this stage (with thanks to Audax!).

[Mark B]

On some makes of vehicle, I have known CPS failure to be temperature dependent. i.e. the car stops and when the breakdown service arrives it has cooled down a bit and starts again.  So just in case your car starts now that it's cold doesn't mean to say it isn't the CPS.

Sgould, I am not sure you are correct about the fuel pump being pressure controlled.  In my experience the fuel pump controller tells the pump to run for a few seconds when the ignition is turned on but then stops.  It starts running again when the engine starts.  If the engine stops, for example after a crash, the fuel pump stops so that fuel is not pumped out of broken fuel lines to reduce the fire risk.  If it was pressure controlled, fuel would be pumped out of a broken pipe as fast as possible.

[mikeloadsasaabs]

On some makes of vehicle, I have known CPS failure to be temperature dependent. i.e. the car stops and when the breakdown service arrives it has cooled down a bit and starts again.  So just in case your car starts now that it's cold doesn't mean to say it isn't the CPS.

Tried it again this morning, still dead as a dodo 

[Audax]

On some makes of vehicle, I have known CPS failure to be temperature dependent. i.e. the car stops and when the breakdown service arrives it has cooled down a bit and starts again. 

That is very much the common failure mode for a Saab CPS failure, I have known only a couple of cars just die like this and put a code in. I'm at work so can't read the diagnostics for that code though.

[mikeloadsasaabs]

Just had a call to say the new CPS is on its way, should be here Thursday - €178 including express delivery from Sweden 

[Audax]

Just had a call to say the new CPS is on its way, should be here Thursday - €178 including express delivery from Sweden 

!!! that's £140! I'd have thought someone could have got one to you in that time scale from the UK for less than £77 shipping!

For example neo brothers have genuine crank sensors in stock for £63 and the example shipping is £21 for a 4 day service to Austria.

[mikeloadsasaabs]

Just had a call to say the new CPS is on its way, should be here Thursday - €178 including express delivery from Sweden 

!!! that's £140! I'd have thought someone could have got one to you in that time scale from the UK for less than £77 shipping!

For example neo brothers have genuine crank sensors in stock for £63 and the example shipping is £21 for a 4 day service to Austria.

Ah, but the one from Neos isn't gold plated 

Yes, I know it was expensive, but given that we only have the one car and I had no time today to research alternatives, I went for the easiest option to ensure I got a pukka part that will last *sigh*. Ah well, it's only money. And it's the first one I've bought in 217,000 miles 

When I got home this evening I removed the large heat shield and soaked the screw holding the CPS in WD40 - it was bad enough getting the can into position to spray that accurately. I have the torx ratchet driver ready to go. Tomorrow, the old one comes out hopefully.

[mikeloadsasaabs]

When you are checking the resistance, are you checking between the pins on the connector, or are you checking the pins to earth?  The reading is across two pins, not to earth.  Only one pair should show a reading and that should be in range.  If its not, the CPS has gone.

Doh! I was checking the readings on the loom, not on the CPS connector   No readings at all across any combination of two pins.

Old CPS unscrewed and ready for removal. I've managed to lose the invisible clip that attaches the lead to the water pipe 

Just had a phone call to say that the new one has arrived. Unfortunately I have no means of getting to collect it today, but have made arrangements to borrow a car tomorrow.