Hyundai Repair: 2002 santa fe lx (V6), o2 sensors, gas mileage

Question
A few months ago my check engine light started coming on and then would go off by itself after a few days, but now it has been on for a few weeks so i had it checked out and the mechanic says it has error codes P1166 and P1167.  I have'nt noticed any changes myself, but are there any performance issues as a result of this problem

Answer
Hello Steve,
These two codes showing that both front and rear O2 sensors on bank 2 are having troubles to read and compare the exhaust gas. It usually does not have any symptom because computer works hard to compensate. It efects the gas mileage. That code is usually set by a faulty front O2 sensor. So, I reccommend you to have your front O2 sensor replaced on Bank 2.