Thanks Dandeman, As for your question, no, I don't do off-road.
I had an oil change less than 1 week before my engine light came on the first time. (just thought I'd mention)
Do you think I should just go ahead and let toyota change this sensor for me ? At least it would be guaranteeds with their work and 12 months on part ( I think) whereas with another mechanic, nothing would be guaranteed, right ?