Problems with O2 Sensor and P0138 code

Got a 2010 Tacoma TRD Sport last year and so far it's been awesome. First Tacoma and first truck. And my first real foray into doing work myself on my truck. I've avoided dealerships but still generally paid other people to do it for me. With this truck though I felt like tackling stuff myself and hopefully will even get into some mods eventually.

Long story short my most recent adventure in self maintenance was replacing an O2 Sensor (big deal I know, ). anyway it seemed to go really well, got rid of my P0136 code except 50km later I started to get a P0138 code. I'm going to try disconnecting the sensor and cleaning the connections and disconnecting the battery tonight, hopefully that'll take care of it. If not any suggestions? Brand new sensor so I don't really think it's that and I'm not really sure what else to do if it's shorting somewhere.