I have a 2002 Seicento sport with and intermittent starting problem.Very occassionally no matter what the weather the car wont start in the morning after standing overnight.It was recently serviced and no apparent fault was found.The car turns over ok and if left for 20 minutes it starts perfectly and can go for weeks without any problem.It always runs very well with no problems.
Has any one got any ideas as to the possible cause?

sensor related, ECU related?

I'd investigate earth problems and the crank sensor.

Liam