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Join Date: May 2011
Had the same issue with my 156 1.6 TS. The engine would "die" instantly during a traffic light stop or in a gear change. We never figured out the problem but this stopped when I replaced the thermostat. What I presume was the issue, previous thermostat was always open, the engine was operating heavier and thus, RPM's would drop to 0. Never happend during 1st start or, in other words, as long as it was cold. Also, it would start again immediately as if everything was fine. Never happend during driving where acceleration pedal is pressed.
Now, I understand I am talking about a different car/engine/technology but apart from that, it's the exact same story. Also I must note that examiner would always point to the RPM sensor (do not know the exact english description) but this never solved the issue since we had changed the sensor more than once.
Furthermore, another 156 who had the exact same issue as your 159 (engine would cut out during driving) solved the problem with a new (well, used to be exact) ECU.
I hope the above can help you in a way to identify the problem as I fully understand how you feel. Myself was in a constant readiness and that was pretty stressful.