Hello,
I just bought an A6 2.5 TDI Allroad (AKE). The problem was very poor performance. ONLY UPHILL with 1st gear.
Okay, the fault code reader indicated: "Intermittent intake manifold vacuum pressure regulation difference!"
I then discovered that the VTG adjustment had no effect whatsoever when the engine started. After checking the vacuum hoses, I identified the failure of the N75 (charge pressure) solenoid valve. I replaced it, and as a result, the VTG correctly returned to its position. I then tried to start the vehicle, but I was unable to give it any gas because the vehicle was emitting extreme amounts of smoke, and it was also impossible to get it to rev above 1500 RPM
Then, start Vag-Com again, and a faulty AGR is detected. Okay, print cartridge checked - okay.
Then also replace the corresponding solenoid valve (which is located next to the charging pressure regulator valve). And I have come to the conclusion that it is defective. So I also replaced this valve, and the car is running perfectly!
Since the whole situation seemed quite strange to me (HOW COULD BOTH VALVES BE DEFECT AT THE SAME TIME), I decided to examine the valves more closely and open them. And here's the thing: there were salt deposits inside the valves. These had penetrated into the valves through the air filter box, via the ventilation hose (which is attached to the air filter box for atmospheric pressure), When I opened the air filter, I saw a horrifying sight: It was completely full of saltwater and dirt, which had been sucked in by the snow.
Is anyone familiar with this? How does all this stuff get in there? Is there a solution to the problem?
Best regards, Luigi