Toyota Repair: Lamda sensor, toyota claims, toyots

Question
I own a Toyots Rav4 2000 model and my engine warning light has come on. Toyota claims I have to replace two lamda sensors but the OEM is too expensive. I have found DENSO brand with half the price. My question is should I trust an aftermarket lamda sensor such as Denso? Furthermore I was told that if I replace with an aftermarket lamda sensor the engine warning light will remain on. Is that true? Thank you

Answer
Not necessarily, Denso actually makes a lot of parts for toyota so as long as they are installed correctly and it was diagnosed correctly in the first place I don't see why they won't work. Rav$s also have a lot of problems with catalityc converters so be sure the cat is not the real problem.