Use 16 gauge wire for all the wiring and you should be fine. Youll need one short and one long for a header install.

O2 Sensor 12 Inch Extension Harness Flat Connector
Extending o2 sensor wires. The long o2 extension is for the rear bung and the short o2 bung is for the front bung. Only 18 left in stock order soon. The wires on the sensor section are no different then the main harness. New oxygen sensor extension wire harness 24 inch fit for subaru wrx sti outback legacy impreza. Inside the o2 sensor connector there is a cal resistor. The key thing is to use teflon or high temp insulation wire to avoid heat damage to the wiring.
Plus i think you can buy one from them as well if you dont want to cut. Get it as soon as thu jul 9. These extension wires are perfect for either instance. Dont cut the o2 sensor wirecut and splice on the gauge side of the o2 sensor. This is the harness wires plug im talking about the denso oxygen sensor i have is still new perfectly fine. Alright so one of the wires i belive to be yellow has snapped off at the connector with a piece brokem off inside the plug.
I think the koso has an extension cable on it. Since the o2 sensor is voltage based extending the wires either on the sensor or on the actual harness between the sensor and ecu will increase the resistance of the circuit. If i had to extend wires i would remove one of the connectors either sensor or main solder some extension wire using the same gauge then add new connector terminals to the extension. So it doesnt matter if you extend the o2 wires or the engine harness wires ohms law prevails. The o2 sensor is the only thing that draws any power so it needs the 16 gauge wire. The o2 signal wiring can be 18 gauge.
50 out of 5 stars 1. Oxygen o2 sensor wire for 2014 2017 jeep grand cherokee dodge durango challenger viper 24l 30l 32l 36l 57l 64l 84l v6 v8 v10 extension.