o2 sensor voltage???

[jack-pot]

im wondering about my o2 sensor voltage. i was checking for a vacuum leak using propane and watching the o2 voltage. as i was moving the propane around i found a small leak and the o2 voltage went from .15 volts to .825. after i pugged the leak with RTV my o2 voltage when negative to -.12 and i couldnt get the o2 voltage to come back postive, even when i put the propane into the intake it stayed negative. just wondering what could possibly be wrong?