[m_eli]

So I replaced my transmission (3rd time!) 196,000 KM which is 120,000 Miles. when I got the car back I had a check engine light which pointed to Oxygen sensor (I think). Replaced that. Now I am only getting about 10.5 mpg. I don't know exactly but based on frequency I was filling up, I think I was getting about 15 MPG prior to transmission replacement.

What should I do?

 

[dbx]

So I replaced my transmission (3rd time!) 196,000 KM which is 120,000 Miles. when I got the car back I had a check engine light which pointed to Oxygen sensor (I think). Replaced that. Now I am only getting about 10.5 mpg. I don't know exactly but based on frequency I was filling up, I think I was getting about 15 MPG prior to transmission replacement.

What should I do?

I don't think it's transmission related. It sounds to me like your O2 sensor got fouled up because you might be running rich or there's an obstruction in your airflow... I had a broken catalytic converter in my old Lexus once and it caused the MPG to drop to single digits and a loss of power. It could be a number of things so a bad O2 sensor might just be the result of what's wrong, not the cause.

 

[New Dad New Van]

What is the code?

Did you ever have the EGR valve changed and the EGR ports cleaned as per the TSB. Common problem for our 2001s.