I'm running an uppipe and down pipe, with no EM. Is this what is causing the CELs? I have the Mechanical fix on the downpipe and the resistor on the uppipe. The car doesn't seem to run any different with these codes. P0139 is O2 sensor reading slow, how do I make it read normal? P2096 Post catalst fuel trim system too lean bank 1, does anyone know what that means?