Please help - A4 B6 ALT 2.0 Engine abruptly cuts out and will not start

[cmulindwa]

Hi All,

I have an Audi A4 B6 2002 with an ALT 2.0 Engine. Yesterday as i drove uphill, slowing down to go over a speed bump, the engine suddenly cut out and would not start again - even after trying a few times. It just behaved and sounded like the car had suddenly run out of fuel, even if the tank was half full. Before that, it was running perfectly well, with no warning lights on the dashboard. There were no warning lights even after this, but the engine simply wouldn't start. I called a car carrier and got the car home. I tried to start it again after it came off the carrier and this time it started, which i found very strange. I had waited on the road side for about 35 minutes before the carrier arrived and distance from that point to where the car was delivered is under 20 minutes driving. I am wondering if i have got this problem which i have heard about, where a car drives fine before it warms up, then suddenly cuts out and will not start again until its cool again?

My car now starts normally, but i am worried that it might suddenly cut out if i drive it again. I checked for fault codes using VCDS and there are none on the engine or transmission. Has anyone experienced this before? Any suggestions on what i should check, would be very helpful. That there are no fault codes is quite disturbing! Could it be related to fuel pressure or vacuum leakage? I guess if it was a failed part e.g. a coil or fuel injector it would have shown on the vcds, right? I will appreciate all the advice i can get here. Many thanks. Charles.

[Crasher]

With that fault pattern to me it is classic crankshaft speed sensor failure.

[cmulindwa]

Many thanks Crasher, let me check that out. But would it not register a fault code on VCDS?

[Crasher]

The G28 hardly ever comes up as a fault, that is one of the clues.