Had a P0057 code for a while. Today I jacked up the X and got the multimeter. Did some diagnostics per the fsm. Battery voltage was 12.45 - voltage through the harness connector was 12.1. thinking that was because of a not perfect ground (used the exhaust ground behind the cat). Tested the harness on the sensor. Resistance between terminals 2 and 3 was 11.1 ohms, no continuity between the others. 15 A fuse is fine. No visible damage to the harnesses and wires on either side. Its an NTK O2 sensor. Maybe Rock Auto sent me a bad cat. '09 OR Any other ideas?