oil sensor and abs lights SOS

[sirlasc]

Recently My Car Present To Failures.
First The Oil Sensor Light Turns On, And Suddenly Turns Off All The Time. So I Would Like To Change The Oil Sensor, But I Cant Find It Under That Name,can You Please Told Me Whats The Name Of This Part And Where Is It?
And Second The Abs Light Turns On, And Suddenly Turns Off All The Time, The Audi Scanner Tells That Theres An Oversignal (as I Remember)in The Front Left Wheel, I Changed The Sensor But Still The Same Trouble, Before The Abs Light Comes On, I Can Hear A Noise Like Metal Friction, Someone Tolde Me That Is The Abs Gear, Could You Please Tell Me If This Is Correct? And Whats The Name Aof The Part Im Looking Forand Where Is It?

Thank You So Much.