Thread: Regrounding the O2 Sensor

I still have to wear out my NGK copper plugs. Just like my new NTK-D2F O2, only diff was this cheaper (still $150) O2 didn't had the tiny stamped Nissan logo without the text 'Nissan' in it.

so this works great idle is more stable and afr's are more stable. but my actuall problem still persisits. cause it's time for the new bin.

i am lost u only need to do this if you run a header?

Yes, because your stock cast iron header is a great conductor. I still run the 4 wire o2 sensor on my stock header cars though, it's cheaper then a Nissan replacement.

um, idk if it was covered in the last 31 pages, just incase its was not,
on the oem cat flange on the p11 theres a braided ground connect to the left hand side of the cat bolt by a gounding washer (facing the engine) and the other end is connected to a bolt to the support rod for the left hand side rubber damper/hanger. i suppose nissan already figured it out at this point if the b chasis lacked it? or maybe they already had them, just when we take our stock secondarys out we mearly throw them away thinking nothing of it. i know i have! which is why im going to reinstall one i made myself. good thread, had no idea!

Yup that's part of the reason OEM cat ground is there. But another reason is probably because of rear O2's on older cars. I know that on 98+ they started using 4 wire sensors for CATs too.

Since my 94 USDM SE-R is not wired up , color-wise, like the diagram, and someone said to just use a multi-meter, my question is a basic one. Do I just turn on the ignition and check for 12V at the harness plug side to locate the two heater wires? It makes sense to me, but someone else said it's "always the two outside posts in the plug". Getting around 19mpg with the stainless header seems way to low to me, even though sometimes I check that it still revs to 7400 every once in a while. I just want to make sure before hooking up my Bosch 15727, as it's my daily driver. In other news, I re-grounded the MAF also. I hope this helps others also, as the question not asked is usually the best one.
Thanks, Chuck

Heater wires generally will be the same color. Check the first post for wiring diagram too.

just redid the 4 wire job that was previouly installed..(like 3 feet of extra crappy wire),just retraced each individual wire down to its connection


*bosch 4wire sensor* to nissan harness(93 nx2000)

black wire ---------------------------- fat grey wire with withe stripe(has shielding under insulator)
gray wire ---------------------------- is ground(blue in pic) and goes to rear of intake manifold)
white wire ---------------------------- black wire with grey dots
white wire ---------------------------- white wire with green stripe

Hello guys,
Im instaling a OBD1 ECU and the harness did not came with O2 sensor or the conectors, so im using the o2 sensor from my old OBD2 harness, it is a 3 wire O2 sensor.

I know from what i readed that the white wire (middle) is the signal wire and goes to the pin 19 of the OBD1 ECU. But the 2 other wires for the heater i dont find in the OBD1 ECU pinout where to put them, any help?