this is a picture showing the bank 1 location. http://chinasinoy.com/service/bank-1-location-84.html for p0133: The simplest thing to do is to reset the code and see if it comes back.
If the code comes back, the problem is more than likely the front Bank 1 oxygen sensor. You will likely wind up replacing it but you should also consider these possible solutions:
Check and fix any exhaust leaks Check for wiring problems (shorted, frayed wires) Check the frequency and amplitude of the oxygen sensor (advanced) Check for a deteriorating / contaminated oxygen sensor, replace if necessary Check for inlet air leaks Check the MAF sensor for proper operation