Audi A3 2006 2.0 TDi 170 stalls/cuts out

[markj1978]

Hi my car has developed this issue recenlty where it will start idle ok and then randomly cut out as if the ignition has been turned off. Turn it off and it will start again fine. It will also try and happen when driving as it randomly loses power and slows down for a second or two then will take off again.
when this happens the rev needle will flick and drop as iff its been turned off. Also sometimes after one of these 'twitches' the glow plug light will come on and start flashing. when you turn the igniton off and restart it goes away. car runs fine with no loss of MPG or turbo boost when this isnt going on.
Audi has just replaced all the injectors as part of a recall which i hoped would fix this but is hasnt.
I have ordered a VAG reader but it hasnt arrived yet so dont have any error codes as yet. Anyone got any ideas?

[chittychittybangbang]

Sounds like an electrical problem, could be anywhere from battery-alt to cluster-ecu grounds/connections. It could even be a bad ignition switch - car thinks you're turning it off.

[markj1978]

thanks for the reply. Electrical issue was my take on it as well. I thought it might even be the immobiliser. Any ideas on where and how to start fault finding it?

[chittychittybangbang]

easy way to check ignition switch, use vcds and monitor ignition key status while wiggling key. see FAQ for how to replace, easy and cheap enough that worth a try if stumped.

immobilizer won't shut off the car, just shut off immediately after engine start, will throw immo light