W639 111cdi 2007 crank position trouble code

[Durtlocker]

Good morning guys todays little titbit is this
On cold crank in mornings it is or can be a pain ita to start often requiring a jump
Pack , when she does start it comes up with mil light when checked it says crankshaft
Position sensor , what could be the cause of this ? As it will start and run all day as expected. I have done a bit of googling and somewhere suggested timing chain slack could cause jitter thus making an uneven correlation between the crankshaft position sensor and the camshaft position sensor.

 

[Dodipops]

It will be the crank sensor itself, they go temperamental first then fail altogether and then it’s no start.

 

[mersum1es]

USUALLY it is vice versa, warm conditions the start failing, on cold they are ok. But like said, most likely it is either of the sensor malfunctioning.

 

[m80]

As above,
Being the earlier 2.1 (as in not the 651 engine) it has a duplex chain, and it's unusual for these to stretch.

 

[Durtlocker]

Ok guys thanks for that , the code pops up quite randomly about three time so far and tricky to start sometimes other times just as it should I will look for another sensor then ,does any one know if a new sensor will need teaching in to the ecm on adaptions ? Or is it straight forward swap out ?

 

[m80]

I replaced a cps on a 2005 C320 CDI some years back.
It was plug and play.
I would expect yours to be the same.
Do any need coding?

 

[Durtlocker]

Ok I have done the first of two jobs today I replaced the tensioner oil powered bolt which I have to admit has quietened down the old engine a fair bit and I am awaiting the delivery of the replacement crankshaft position sensor which threw another code earlier this morning after first start up before I did the chain tensioning ram.

 

[Durtlocker]

i dont think it will need any coding either as its only a hall sensor i guess