I had a PO171 and changed the 02 sensor and the check engine light is back on. It's a Toyota Corolla 2007. What should I do next ?

pay a mechanic like me, you guessed wrong, and now it gets complex SO many things can do that, like dirty or bad maf sensor, weak fuel pump, intake manifold vacuum leaks. But you can check those if you know how to test them

Hi, the mechanic told me that it was the 02 sensor and when he replaced it, the light is still on. So my mechanic was wrong and they tried to sell me the wrong part. Scotty, I do my homework and that's why I thinks it's the intake manifold gasket.