Hi i bought a used 2002 Sentra GXE WITH CALIFORNIA EMISSIONS. The car was getting a P0138 , on a scan tool B1S2 showed a constant .300mv the corresponding short term fuel trim says N/A. I replaced the ox sensor and now it shows on the scanner O2 ready where before it was not. Is that normal for the fuel trim to be N/A. Do I need to drive it more , will it pass emissons?