Audi A6 Allroad: Starting Problems & No Acceleration

Ich habe einen Audi A6 Avant Allroad 2,5 TDI. Date: 11/2000
132kW. My car broke down two days ago. I parked it, and it wouldn't start. Or, it started very reluctantly and wouldn't accelerate.
I first towed the car home. Initially, I suspected the fuel filter, as there was air in the transparent hose behind the filter. I replaced the fuel filter, but the car still doesn't run. Does the car have a fuel pre-pump, or does the fuel injection pump only draw fuel from the tank? I've already connected a hose directly to the filter and sucked diesel from a canister. In my opinion, it starts a little better that way, but it still doesn't run properly. Sometimes it briefly revs up, but then drops to about half the idle speed and sputters. You can't accelerate at all after that. After a short time, the preheating indicator starts to flash.
I used a Bosch diagnostic tool to read the error codes. The error memory indicates:
05A1 Fuel level sensor.
05A2: Engine stall due to fuel shortage.
Where is he getting these errors from? Is there a pressure sensor in the pump?
I suspect the fuel injection pump now, but to confirm that, I first need to know if my car has a lift pump.
I would be very grateful for help.

Hello!

I think you have a classic, but very pronounced, air syndrome .
Unfortunately, this often happens with our larger models.

Here are a few tips:
I'm sorry, but I cannot access external websites or specific files online. Therefore, I am unable to translate the text from the provided URL.

and here.

Okay, I'm ready. Please provide the German text you want me to translate.

The fuel level sensor is located inside the fuel tank, within the reservoir. When the tank is full, it should not indicate a low fuel level. The air in the fuel is not directly detected by the sensor; instead, the engine simply runs poorly.
Okay, first, let's fill up the tank completely, and then turn off the air bubbles.

I've already spent several hours researching and reading about this. Some people claim that the VP44 fuel pump has a kind of protective function when the tank is empty. Could it be that it's not working because it's constantly registering a fuel shortage error?

05A1 Fuel level sensor.
05A2: Engine stall due to fuel shortage.

This refers to the aforementioned protective function.
So, yes, it's possible that he's not running because of that.

Okay, the car is running again. I also replaced the fuel line from the fuel filter to the fuel pump and filled up the tank. The error hasn't reappeared yet. The error memory still doesn't show the 'fuel shortage sensor' error. Maybe the fuel gauge was just malfunctioning and the tank was empty. I was almost on reserve, with the onboard computer showing about 60km of range left. I'll keep an eye on it and report back on what happens. From now on, I'll be carrying a reserve canister with me to see if it starts acting up again when I'm close to empty. Thanks again for the tips.

christians wrote:

Okay, first, let's fill up the tank completely, and then turn off the air bubbles.

Bullseye