O2 SENSOR
I chose to use the stock Toyota O2 Sensor for the Closed Loop (Narrow Band) input signal to the E6K.
It is a four wire sensor, just follow the installation outline in the Haltech manual

WIRING NOTE To use the stock sensor
Brown is ground.
You need to twist the heater + and the O2 Sensor + together
The O2 Signal wire is the Sheilded Wire
This allows the stock Four-Wire Sensor to connect to the Three Wire inoput of the E6K