If I replaced the oxygen sensors and reset the service engine light, what could cause the light to come back?

I have had many times the scenario where a fault code was related to O2 sensor and had that replaced but, in fact the code was triggered by something else. Most of times, if the O2 sensor is not the faulty component there is some other reaction causing that fault code to come up. A lot of times I have found a very small exhaust leak at flex pipe.

This is very common on Accent's and Elantra's. With a little crack or hole in the flex pipe, there will be extra air sucked into the exhaust system causing O2 sensor to read the excess of air and with that would command computer to increase the amount of gas distributed to the intake gallery causing at the same time excessive fuel. Have the mechanic inspecting the exhaust system with caution and see if he's able to find any small cracks or pin-holes.

How do you know he actually replace the sensor/doesnt sound right/the sensor wires are on them and they go to wire harness/what the devill is he talking about/i smell scam.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.