Recently, I noticed that my rpg are going up and down sometimes when car is not moving (gear is P or D with pressed brake) and interior lights are unstable too at that moment. I guess it's some kind of electrical problem. Any ideas? Did anyone experience this?

This doesnt happen every time, only once or twice a day. Car is running normally otherwise.

Car is a4 B6 2.0 with automatic gears

Thanks

 

Try having your battery and alternator tested. When were they last replaced?

Cleaning the battery terminals can also be done.