(T) Stilo 1.6 sudden cut-out

Hello, i need some advice regarding this fault:
My Stilo 1.6 (2002) suddenly cut out after driving 100 meter with cold engine.
Engine did not start, waited few minutes and engine started but cut out again before i reached home.
Reading the fault code P0335 indicated the crankshaft position sensor - as i already read about this known problem i replaced it.
Car ran fine after replacing but two days later i had the same problem - car started, but cut out while i wanted to drive on with a cold engine.
After a few cut-outs i managed to drive home without any problem.
My code reader gave me the same code P0335 but i can't imagine the new sensor is faulty too so i guess this must be a poor contact somewhere?
I wiggled the connector and cable of the sensor under the air intake, the connectors on the ecu and the D4 connector but i can't reproduce the fault.
Has any of you ever had the same problem and did you find the cause?
Until now my Stilo gave me very little trouble but i don't like the idea it might cut out randomly....
I hope this is a known problem for some of you and you can point me in the right direction, thanks for your help !
yellowstilo

P0335 Crankshaft Position Sensor A Circuit Malfunction
So it's telling you the problem is in the circuit itself and not necessarily the sensor. As you've already replaced the sensor then the fault will be from the sensor connector to the ECU and could even be inside the ECU.

I'd pull off ECU connector B and check the resistance from there through the crank sensor, it should be quite low, around 1kohms.

Here I'm checking the crank sensor resistance at its connector


but for your problem I'd want to check the whole wiring so i'd check it at the ECU connector B and that's on pins 9 and 23

Then it's best if you can, to try and catch it whilst it's in the fault condition and check resistance again then. If it's still the same then the fault is either poor contact between the connector B and the ECU or within the ECU itself where there may be a poor contact between the ECU circuit board and the connector

thank you for your quick reply, i already noticed the connection to the ecu is running trough 2 connectors which i will check for continuity from the ecu side.
As the car ran fine when the temperature raised it could be a temperature-related problem.
I just hope the fault isn't caused by the ecu itself, in that case the repair will become more expensive...maybe i will resolder the corresponding pins on the circuit board before replacing it.
thanks again for your very good explanation, i will report back as soon as i solved this problem !

Well, here's my update regarding this fault:
today i connected 2 wires at the ecu connector to monitor the resistance and the voltage output of the RPM sensor.
Resistance was 1090 ohm (ok) and voltage was 2.15 volt at cracking (o.k. too).
Wiggling of the cable loom and connectors didn't make any diiference so i suspected the fault was in the ecu itself.
I was lucky to have a new, virgin ecu in stock which i bought on Ebay some years ago and decided to change the ecu's.
At key-on i gave it some time to store the immobilizer code, then started and yes! te engine started rightaway!
Because a new ecu needs to learn the values for the phonic wheel the MIL blinked and the beeper beeped continuously - so after a decent warm-up ride i revved the engine 3 times up to almost 6000 rpm ,let it drop to idle and the MIL warning and beeping stopped rightaway!
So unfortunately this was caused by the faulty ecu and not by the sensor or it's wiring.
I just have to reflash the new ecu with the newer 2616 software (with the throttle body update) because it now has the 2611 software.
As i have my own Examiner Smart and some flash cd's i will give it a go some other time (with the battery charger connected to my battery to prevent a faulty flash writing....)
I want to thank Deckchair again for his help and suggestions, this forum really is very valuable for Fiat owners !!

i just opened the faulty ecu, pin 56 of connector A has come loose from the pcb - according to the description this pin is Not Connected (managed on CAN line) but i will try to push it back in position while resoldering it.
Maybe i can make a good spare ecu out of it....
Picture is not very sharp but you can see 1 pin being higher than the rest.

on closer examination with a magnifier glass i noticed more pins with bad soldering joints - i will resolder all pin connections and am confident this will solve the problems of this ecu, i will post the result after testing it !
So if you experience the same problems with your 1.6 Stilo this might solve your problems too....

where does the ECU actually mount...sounds like heat issues.

the ecu is mounted on top of the front camshaft housing on the right side.
I always have wondered why Fiat choose such an odd place to mount the ecu - too much heat is never good for electronic parts...

hello.rpm sensor where exactly is the k46 location in ecu.

Sensor K46 connects to pins 9 and 23 of the ECU connector.
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hello. k46 sensor ecu location photo