anti lock, service engine, trac off, brake light all on, ding in speakers???

[sea-doin-it]

The Anti-Lock, Service Engine Soon, Trac Off, Brake lights are all on.
There's also a dinging beep that resonates through the radio speakers.
The lights came on before intermittently, now they're on all the time.
Auto Zone took a reading and said the OS Sensor needed replacing.

This is my neighbor's description of his wifes '02 I think, any help?