matthewr87

We recently returned from a three week trip. I placed the Cayenne on the CTEK so that the LiPOS battery wouldn't be fubar'd. First thing I noticed is that the car was sitting much lower than normal on all 4 corners. Perhaps I have a leak somewhere in the suspension system? The second thing I noticed is that the brake pedal was stiff and almost immovable. I had to really stomp down hard on it to get it to trigger the interlock and allow me to start the car. Anyone else experience these problems with a car that has been sitting around?

justabout

I’ve had cars where the bake booster vacuum reservoir leaks out completely if the car has been siting for a week or so. Rock hard pedal until the engine is started. Most cars don’t do this.

matthewr87

I'm wondering if there is a leak in the brake booster vacuum reservoir then. I've never encountered this before in any other car. With the Cayenne it has happened even if not driven for just a few days. Guess I'll have to make an appointment at the dealership.....

kayjh

Mine does this occasionally after a week sitting. I notice it because I press normally on the pedal and turn the starter and nothing happens. At that point I realize the brake pedal needed more force (quite a bit actually), then the car starts and everything is normal.

matthewr87

Hmmmmm......could it be "normal" for Cayennes then? You also have a GTS yes?

retom

I wouldn't worry about the brakes. It often happens after a long standstill that the servo loses pressure. This is normal.
I would be more concerned about the loss of pressure in the suspension system. This could mean a leak in the air spring system.

Ironman88

I had this exact same problem with my 2021 Audi SQ5.

The problem was addressed and rectified via warranty per the Audi TSB attached below.

retom

Yes, but OP's problem appeared after 3 weeks of standstill.
I had this phenomenon in several of my previous Audi Q7 and Q8. Often after a long standstill the brake pedal would become hard. After starting the engine this phenomenon disappeared immediately. It is simply normal that the servo is not able to maintain pressure during a long period of non-use. I have never worried about it.
However, all my 4 previous cars that had air suspension never lowered themselves even after a long period of standstill.

kayjh

Yes.