bank 1 oxygen sensor

hello all... i recently had a mechanic change the bank 1 oxgen sensor (the one before the convertor)....but the problem now is the service engine soon light keeps coming back on for the same problem....he erased it and i erased from the code.....i dont know what to do!!......p.s...i keep erasing it with a OBD2 code reader machine.......thank you!!!!!:banghead:

What code is he getting? It's possible that it's not plugged in, was a faulty sensor, has gone bad like the former, wire damage, etc.

What code is he getting? It's possible that it's not plugged in, was a faulty sensor, has gone bad like the former, wire damage, etc.
the code were getting is (171)....

That is a DTC for fuel trim lean. The HO2S is probably doing it's job, you need to find what is causing the HO2S to stay lean. You probably have a vacuum leak somewhere or low/restricted fuel pressure. You're not running E-85 are you? I promise you that E-85 will set lean codes with that vehicle or any other vehicle not designed for E-85.

what is e-85??

85% ethanol fuel
If you read some other posts about ethanol you will see that you need a richer air/fuel ratio with ethanol