Ok got a question for everyone. I have an 04 wrx with a 2.5 Forster motor in it. Put a new vf39 turbo on it and cold air intake. Took it to get a tune on it and found out the O2 sensor was bad. Replaced it and put maybe 50 miles on it before taking it to get tuned. Found out the same O2 was bad. Just put a new denso O2 on and with in two mins the check engine light came on saying the O2 was bad again. What could be going on?