Fan-belt tensioner went in my car and had similar symptoms to OP. Fan belt runs the alternator and power steering pump. Not sure if same with all cars. Lights went dim, battery light came on and power steering went. No oil light, however. Leaves you stranded and can be awkward to get at to replace (i.e. pricey at a garage: labour)
Timing belt is a whole different world of pain as mentioned by other posters.
Timing belt is a whole different world of pain as mentioned by other posters.