I have a 2001 Audi A6 2.5TDi (155BHP) and a few weeks ago, I put some fuel in and about an hour later it started to lose power. The exhaust then started billowing thick white smoke and the engine was misfiring as well. The following morning the car would not start at all and had to be towed to a garage. I had the fuel in the tank checked and the fuel was found to be fine.

The initial diagnosis was that the fuel pump near the fuel tank wasn't working and had to be replaced as there was no fuel coming through to the engine. This was ordered and fitted, but the car still would still not start. The ECU was checked and found to be fine, but was not picking up the fuel pump in the tank. I was told it was a wiring problem and had to go to another place to be fixed. The second garage was a specialist diesel place and they diagnosed the fuel pump at the front as being faulty. They replaced the part and the car still had the same problem. They also checked the electrics and found everything to be fine. The ECU is also not showing any faults.

Any ideas? I still have the two garages trying to bill me for the two parts they fitted, but which haven't made a bit of difference to the car.

 

Since you had white smoke, I would say it's the injection pump, not the fuel pump. White smoke in diesels usually means it's blowing out unburnt fuel.

 

Have you resolved this problem? I have the same with my A6 2.5 tdi 2001, but it fixed itself for a day now it's doing the same again, struggles to start then fills the street with white smoke, runs in limp mode and the traction control light comes on, smoking non stop

Kind regards
Moxey