Hello Audi Techs, I am hoping someone can lend a hand, I sure would appreciate it very much and thank you in advance.

My Son who is in the ARMY has a 2004 Audi A4 1.8T he shipped from Germany here to the US, We've had oil pressure light and check engine light problems for vacuum leak. I took the car to Audi and paid a fortune last year to have the oil problem fixed, six months later the oil pressure light started coming back on again. Later, I found that I was having a Fram Oil Filter used instead of the smaller one that is required, this corrected the problem with the oil pressure light, it stopped. Later, the check engine light kept coming on for emissions leak, so a new valve was needed and replaced, this allowed me to smog the car in California.

The check engine light came on recently and says it is a large vacuum leak. My Mechanic has tried a lot of things to find the problem, but couldn't find it. Later, he pulled the suction hose that goes into the Intake Manifold and this has solved my check engine light and oil pressure light problem.

My question:

The hose needs to be plugged into the intake manifold I know, but what can I do to repair this problem?

Will it damage the car if this hose is not plugged in?

Is there a Sensor inside the Intake Manifold?

Am I able to reset the computer by disconnecting the Positive Battery Cable and stepping on the brakes 3-5 times?

Audi wants me to spend $295 to check this problem, they refuse to answer any questions, and to be perfectly honest, I've spent $5500 for small stuff they keep charging me for, this has gone over board, each time I've taken the car in and get it back something else goes wrong, the car has 85000 miles.

Any help would greatly be appreciated for my Son and I, thank you.