Q regarding o2 sensor ground

[tloh]

OK redoing my sr20det(red) engine harness. Was wondering does the O2 sensor ground need to go to the ecu ground wires or can I run the o2 ground straight to the chassis? Didn't know if it used ground resistance or not to read from ecu (via NDS or aem)

[Kingtal0n]

the O2 grounds through the exhaust. You probably mean the O2 heater ground, which can ground to any ground, like the chassis.

Its just for the heater. You don't even need it hooked up. Only the Signal wire is important. The signal wire will work without the heater, but it will take longer for the O2 sensor to start working.

[tloh]

That's what I thought on 3 wire but wasn't sure. Thanks. some reason o2 isn't showing up in NDS just reads 0. I seen the ground was unhooked in the harness, wanted to make sure that was not the cause.