Engine just dies!

[trixilator]

Driving in slow traffic my 5 year old fully serviced (5months) automatic Vauxhll Vectra 2.2 just died in the middle of a pedestrian crossing! I switched off tried again and off we went - a quarter of amile further on, same thing happened. Switching off for a minute then re starting seemed to fix it. I made my home via side roads rather than my usual motorway route in case it happened again. This happened about 6 weeks ago as well and in trying to think what was similar on the trips, can only think it was because I had the air conditioning on. What normally would cause this - battery, alternator? Being automatic, I couldnt push it to the road side. Happening on the motorway would be a disaster!
Any suggestions much appreciated.

[Count-A-Strong]

Could be any number of things. Altenator being one of them. Does the battery light come on before it dies?

[trixilator]

Didnt notice any warning lights before the incident - when it died the battery and oil lamps were lit

[Count-A-Strong]

F the battery light comes on then it's the altenator. Could also be the engine mapping needs looking at / re chipping. A problem with a thermostat sensor or emissions sensor. Like I said, any number of things.

[trixilator]

Many thanks Count-A-Strong - maybe I'm going down wrong road (pun!) concentrating on the A/Con - will get it checked out. Appreciate your in-put.

[razza]

I used to have a granada do the same thing on me,after about a year of this and several visits to mechanics,even a ford technician it remained unsolved.One day while in middle of town it stopped and wouldnt restart,green flag came and driver asked me what was the matter,explained to him how it had been doing it for a year and the symptoms he said it was ignition booster,new ignition booster cured it.

[AlBags]

Count ..
That's misleading him.
Alt and Bat light come on as soon as the engine is killed. It will not be alternator. Extremely rare to cause a fault like that.
Usually it is an electrical component failing when hot, then ok again when cooled down (like a coil)
You need to plug into a Scanner or diagnostic to read any fault codes.

[Graham-W]

"Being automatic, I couldn't push it to the road side. "
Why would being an automatic be different to a manual?
Just put it in neutral ( not park) and push away to your hearts content.

[Count-A-Strong]

Albags. My daughter has a Golf which did exactly the same. The battery light came on whilst driving, then the car cut out at idle. It was the altenator.