A4 1.9 TDI Engine Failure: Causes & Fixes

'I once had starting problems with my Audi A4, 1.9 TDI, manufactured in 1997, with 110 horsepower, which were resolved after replacing the fuel filter. Since then, I've been experiencing a problem where my car suddenly stalls, and the battery almost completely discharges before it restarts. This has happened three times so far, and the diagnostic system hasn't shown any error codes, leaving the workshop puzzled. Replacing the voltage supply relay didn't help. Otherwise, the car runs flawlessly for weeks at a time. The problem occurs when the car, which was previously warm, has been standing for a short time and the engine is still slightly warm. Within the first 500 meters after starting the car, it suddenly stalls. Does anyone have any advice?'

I had a similar issue with my Sharan. There was a fuel line that had been chafed (by the black engine cover).
'As a result, I had a very small leak where air was being drawn in. So, after some time standing, the fuel would always flow back into the tank, and I could drive, drive, drive without any error being stored. For me, it would always just last until I got to the bakery around the corner. I would get my bread rolls there, and then nothing would work anymore in front of the store.'
After replacing the hose, everything is working properly again.

I would also suspect a connection to the filter change. Make sure the O-rings are properly seated in their grooves and not pinched. Is everything around the filter tight? Are there any bubbles in the transparent section of the return line?

Hi!

It could also be the air shut-off valve, which might be stuck, or (as it was in my case) the battery isn't providing enough starting power, causing the TDI engine to turn over too slowly to start. I experienced some significant starting problems. Replacing the battery resolved the issue completely.

Thank you for your suggestions. We discovered yesterday that the 'experts' at the workshop had simply forgotten to install the O-ring, which caused the fuel filter to draw in false air. I hope this problem is now resolved. Should we be able to hold the workshop liable for the costs incurred in the meantime?