Dual O2 Sensor Wiring advice needed for install


I’m in the process of adding two Spartan 2 O2 sensors to my carbureted flat 6 engine. One for each bank. I have a couple of questions.

  1. I’m wiring power to the O2 sensors directly from a keyed 12v source. I’m wondering if the sensors will be damaged if I leave the key in the ACC posiiton without actually starting the car? Or does the heater internal to the O2 sensor shut off when it reaches a certain temperature? I’m curious if I should add a dash switch to disconnect power to the sensors in case I want to leave the ignition in ACC position.

  2. If I were to run separate 12v feeder lines from the fuse panel to each sensor, what gauge wire should I use? Alternately, if I was to run 1 wire from the fuse panel and then branch off this feeder line to each O2 sensor. What gauge wire should I use for the feeder line in this scenario?

  3. Lastly, what are you guys using for the LED light that is supposed to let you know whether or not the O2 sensor is running at the right temperature. I didn’t see an LED in the package I received.



Hi Rich,

  1. When Spartan 2 is powered, it will begin to heat the sensor until the internal temperature of the sensor is 780[C] and maintain that temperature. Leaving the key on ACC will not cause any issues unless it is before a cold start, there is a chance that condensation may hit the fully heated sensor and cause thermal shock to the sensor.

  2. The gauge of wire on Spartan 2 is 20 AWG. If you want to run 2 off a feederline, I would suggest 18AWG for the feeder line.

  3. The LED is a very common 20ma 5mm LED. if you send me an email or pm with your order number, I will send you out an LED.

That’s the info I was looking for, thanks!

I did find the LED’s in the bag after all. Not sure why but I was looking for an LED with wires attached so I missed them initially. I did find both of them so I’m all set.