vtraudt

Installed new pads on all 4 corners.
Now pedal feels softer (not 'to the ground', but a bit spongy).
What may be the cause?
What to check?

Garycw

Sounds like air to me. Not sure about if or how any adjustment possible. Mold school on usa cars was back up in reverse then hit brakes to adjust. I'm sure that wouldn't be the case in your duties toon though.
I'll stick to the air in line theory

vtraudt

Did not open the brake lines for the pad change.
Pad setup after change: front/rear press brake pedal several time until firm.
E brake: to release, run VAGcom procedure. When new pads are in, use again (this time" finish pad change") Electrica motor retracts/resets.

Air: only possible way I can see that air got into the system is that I pushed fluid out (since I had all calliper pistons on all 4 corners pushed in). But even then I would assume there is enough capacity in the brake fluid reservoir so that i won't 'suck air' (would be fairly stupid otherwise).

Garycw

Sounds like you know what you're doing. I've not had to have mine changed yet , but I can say if they felt spongy after pad change I'd be disappointed and a little upset.

MP4.2+6.0

Regardless, always bleed brakes w/ pad change anyway. Audi spec is every 2 years regardless of miles. As a practical matter, my pedal is typically firmer after any brake bleed, more so w/ new pads and bleed. Use the current ESP spec fluid.

Garycw

I'd + 1 that. Along with the recommended total change.
On another note , I can't remember ever doing a complete brake fluid change in domestic cars. That does go along with the master cylinder & caliper replacements.
I've learned through Lexus , BMW and now Audi is different where s ounce of prevention is worth 2 lbs of cure