Toyota: possible 2000 echo problem?

I have just had my 'check engine' light come on for the
second time. Several months ago this happened and the
dealership replaced an oxygen sensor within the engine.
Might the have gone out again so soon? What other things
might be wrong or that I might check?

Mike

I've been looking into buy a new Echo. But have been cautious as dealer let me
drive used one(03) and the brakes did not work already.

I now own a 92 Honda Accord EX with only 87,000 and no rust and runs good.

Just have to get my confidence up about the Echo before I buy. Maybe I should
get a Corolla.

Diane