Hi all, I have a 2002 track car that keeps blowing the OXY SEN 15amp fuse whenever I turn the key to start. I have long tube headers and have only the upstream flat 4 O2 sensors. The car will run fine but as I scan using HP tuners scanner, the bank 2 sensor 1, reading are fine at cold start up then go low volts after it heats up. Bank 1 sensor 1 reads good at around .440 volts but pax side goes anywhere from .200 to .900.

Any suggestions as to where I should start with chasing down this probable short? THX!