Oxygen sensor
 

Does driving around with a faulty oxygen sensor cause any damage?, as cant get it sorted for a couple of weeks.

2005 sti

If your sensor is 'reporting' a fixed rich condition to the ecu then it will lean out the mixture by shortening injector pulse. This may damage the engine I would guess by creating a lean condition. If the sensor is reporting a fixed lean condition then the opposite would happen thus running the engine rich. This wouldn't be such a problem.
As you don't know which of these conditions exist I would take it easy until sorted :Suspiciou

It's gone off on its own! Why?