CPS failure with no warning

[mikeloadsasaabs]

New CPS now fitted, and mobile again! Luckily I had the right tools to hand, with a small ratchet handle that fitted nicely.

As a word of advice, I found a directional work lamp, suspended from above into the engine bay pointing at the general area of the sensor, to provide perfect light for the work. The most difficult bit was persusading the sensor to stay in the right place while trying to fit the heat shield and holding the screw to get it started, all with one hand. But it's all done, hopefully for the one and only time 

[sgould]

Well done!

It's the first CPS hat I've heard of that has completely and suddenly failed.  I'm sure it has happened to others, but all I've heard of have failed "slowly".  Do you know if it was the sensor or a broken wire?

[mikeloadsasaabs]

Haven't examined it TBH, I was just glad to get rid of it  . Will take a peek when I have a few minutes.

[Neil of Stevenage]

It's the first CPS hat I've heard of that has completely and suddenly failed.  I'm sure it has happened to others, but all I've heard of have failed "slowly".  Do you know if it was the sensor or a broken wire?

Ditto, and ditto for the cause.......

[Audax]

It's the first CPS hat I've heard of that has completely and suddenly failed.  I'm sure it has happened to others, but all I've heard of have failed "slowly".  Do you know if it was the sensor or a broken wire?

The reason most people don't hear about the rarer sudden failure is that as the car dies they get their breakdown recovery to dump it at the nearest garage, they pull the code see it's the CPS which is usually available in stock the same day, order it up and replace it. I've seen a couple with this problem, it's one of the trinity of 9-5 failures, DI, CPS, fuel pump which can all die with little or no warning!

Mike, just for reference you may want to take note of skandix.de because they appear to have a mixture of genuine and their own parts in stock with cheapish delivery to Austria.

[mikeloadsasaabs]

Mike, just for reference you may want to take note of skandix.de because they appear to have a mixture of genuine and their own parts in stock with cheapish delivery to Austria.

Yes, I've used them a few times, and in fact only last week bought the xenon sensor for the rear axle from them (which I turned out not to need!). Quite useful, as their parts catalogue is on English. Their delivery charges are sometimes on the high side to Austria, so I sometimes have them delivered to a warehousing company just over the border from Salzburg in Germany. We were coming back from collecting the unwanted xenon sensor when the CPS failed on Monday evening!

Thanks for the tip anyway.

[mikeloadsasaabs]

I didn't have a suitable short extension to remove the screw securing the CPS, so I firstly fitted the universal joint that was in the 1/4" socket set that I conveniently inherited with the house:



This was impossible to use because it was too floppy to get into the rather restricted space. So I cut a short piece of plastic conduit and slid it in place to keep the UJ staic. It wasn't load-bearing so no problem that it was only made of plastic:



Did the job perfectly. Unfortunately, while I was packing my tools away, one of the pins for the UJ turned out to be loose, and fell out and disappeared, rendering it unusable. But it did the job perfectly.

[Audax]

Did the job perfectly. Unfortunately, while I was packing my tools away, one of the pins for the UJ turned out to be loose, and fell out and disappeared, rendering it unusable. But it did the job perfectly.

Very much like what I use as a ratchet and driver when doing a crank sensor. How long did it take you with this setup?

[Neil of Stevenage]

The reason most people don't hear about the rarer sudden failure is that as the car dies they get their breakdown recovery to dump it at the nearest garage, they pull the code see it's the CPS ...........

Isn't it true that failing CPS's, (poor hot starting etc,), do not throw up a fault code, and people replace them when poor hot startings appear. before they suddenly fail?

[mikeloadsasaabs]

Did the job perfectly. Unfortunately, while I was packing my tools away, one of the pins for the UJ turned out to be loose, and fell out and disappeared, rendering it unusable. But it did the job perfectly.

Very much like what I use as a ratchet and driver when doing a crank sensor. How long did it take you with this setup?

Not too long, I extracted the old one the day before. I guess in total about 1 hour, mainly working from underneath. The difficulty was in getting a decent leverage to undo and refit the screw. I'd never done the job before, and I could probably chop a few minutes off next time. The total length of the UJ and torx bit was probably a bit less than 4" - there was about 1/2" clearance between the exhaust and the ratchet. I wasted a bit of time trying to find out what was holding the cable underneath all the pipes at the end of the cylinder head. I never did find out, as eventually a clip pinged off when I faffed around with a screwdriver and the cable freed up 

[sgould]

I don't know when I will need to refit a CPS.  I have a cheap set of hex drive bits I bought from Maplins. 



And yesterday I got one of these at the tool stand at the NEC Classic Car show.  Just the ratchet head from this kit.  It's about 4 inches long and takes 6mm hex drive screwdriver heads.  A ratchet version of the tool at the top.

http://www.ebay.co.uk/itm/Hex-Torx-Tamper-Phillips-Flat-Pozi-43pc-Bit-Set-1-4-Drive-Bergen-AT034-/400772143233

[jimmym105]

To add my experiences - a generic CPS failed after 5 years on me before xmas. After 15 years and 125k the original failed. With hindsight the hot starting signs were there before the electrics went crazy on that one. But I was unaware these generic parts are poor! Anyway, the generic replacement failed after 5 years.

Luckily I got into a side road opposite Buckingham Palace before hitting Marble Arch or the M1! It lurched then stalled, would not start until cold. I got recovered and replaced with a genuine Bosch part. Potentially a dangerous failure. Would start and run for about 10 mins, the recovery guy recommended setting off to Sheffield but luckily it went again and I got recovered.

The failed part looked like it had got too hot and some wire was exposed and it'd short circuited.

The only sign was a similar lurch, without stalling, back in July - but it was 35 degrees c that day and I put it down to a  confused car.

Do not replace with a generic CPS!