Hi just got car back today been in garage all day they have been trying to sort the preheat failure warning sign out but they said test showed fault was with heater relay so put new on but made no diffence tested all relays and fuses but no faults found so got car back with same fault anyone got any ideas also all glow plugs tested fine

Have you had 3 good starts to see if glow warning clears...or if use code reader did the fauilt re-appear after clearing with diagnostic equipment.

glow plug relay fuse is a large red one in battery fuse board for quick check..

To go any further an electrical multi meter would be very usefull..further details can be found in guides section on glow plug warning ..as in below link

https://www.fiatforum.com/stilo-guides/151734-dealing-preheat-fault-message-stilo-jtd.html

Hi yes garage said they have check everything they can think of and cant get there heads round it at the moment said they where going to make afew phone calls to see if they can find any more about this issue