Figured since it was wiring related I'd post in here. I put in long tube headers and swapped to a 3-wire heated o2 sensor and just wanted to know if anyone else had done the same and what circuit they'd tapped into to power the heater element. Obviously something that gets 12v when the key is on but is there anything easy in the engine bay to tap off of?

 

All of the 12V+ sources in my engine bay are the same color wire. Pink/black stripe was the color in mine. Your color may be different, but the same method should apply. Just pick any one of those.

Personally, I wired my heated o2 through the fuel pump circuit. This protects the sensor from heating up when the engine is off. I spliced onto the fuel pump side of the relay, right by the connector.

You may need to up the fuel pump fuse 5 or so amps.