Code reader says P0133, can you tell me what this problem should be.

This code indicates typically a "slow response" from the bank 1, pre-catalyst oxygen sensor. You need to troubleshoot for an exhaust leak or possibly a faulty oxygen sensor. You can consult a local shop near you to help you test the vehicle; codes do not determine the failure, but give clues to the technician to help troubleshoot the concern. Good luck!