Thread: Regrounding the O2 Sensor

I dunno. I see people getting this filter. I already have a new original filter for a SR20DE, so I wonder if I would notice any benefit.

Only thing I can think of is less resistance in the fuel line, more stable at the rail?

Just wanted to say that I was getting poor mileage on my car lately, around 20 mpg. I have a ceramic coated down pipe and it was recently recoated after I added a wideband bung to it. I had always in the past been able to get 25mpg on city driving.

I ran a ground wire to an new aftermarket O2 sensor which had not corrected the problem. I just used a ground strap and a hose clamp for testing purposes. With the groundI was able to get 31 on the highway better than I have seen in years.

Next thing is to get a new Bosch 4 wire and get that installed.

I have datalogs of the original o2, the aftermarket o2 and the re-grounded o2. I haven't gone back and analyzed more than the 1st 2 yet. The first 2 show switching rate ( rich/lean ) went way up with the new o2.

My guess is that with the ground issue the voltage read is a little off and the ECU sees the switch to lean a little late making the car run a bit rich.

Hi guys, am new to this very interesting forum and decided to join after having a good read! Am in the United Kingdom and drive a Primera GT Limited Edition powered by the famous sr20de engine. Its a 1999 model and similiar to the G20 that you guys have over at America. I was wondering if you could answer one question that i have. Basically i am having very similiar problems in regards to MPG and after changing, checking and servicing almost everything, I believe the fault lies with the oxygen sensor. Now the problem is that i have a stainless steel manifold wich obviously isn't a very good conductor of electricity and was wondering if this bosch 15727 sensor that everyone is talking about will work in my car????? Its very hard to get hold of around here and i dont mind getting it shipped over from USA.

I just need someone to verify that this sensor will do the job because i believe that you can earth it with the ground wire it comes with. There are some very knowledgeable people on this forum and i would really appreciate if someone could shed some light on this, thank you.

Sorry guys ecu is OBD2

If its a SR20DE or SR20VE this sensor will work (odb1 or odb2). Additionally, if you have multiple banks (more than one sensor), you must replace both (unless you have deleted the 2nd sensor within the ECU).

As for the O2 sensor replacement, email Bosch for the appropriate 4 wire O2 sensor.. But most cars after 1996 (odb2) were 4 wire sensors and grounded properly. If your current sensor is a 4-wire, then your problem is caused by something else...

Good Luck,
Scotty

Thank you very much DC Scotty for your quick reply, i only have the one Lambda sensor on my car and it is the thicker type one with three wires, two white and one black so obviously no wire for the ground, i have grounded the actual sensor to the back of the inlet manifold with a battery terminal around the actual body of the lambda sensor!!! I know it sounds a bit ridiculous but it made a very slight improvement, as of the sensor itself it is in quite a bad visual condition so obviously needs replacing. I will purchase one and get it shipped over from the States, thank you again for your help, much appreciated.

No Problem. Happy to help.
The 3 wire sensor is not grounded with your stainless steel mani. Although you are using a battery cable, this is also a weak ground. You should see dramatic improvements with a 4-wire sensor grounded properly to one of the rear intake manifold grounding screws (this is critical location as all of your other sensors & ecu is grounded there too).

Old worn sensors produce weak & inaccurate signals and the ECU actually incorrectly makes adjustments based on this. After installing the new 4 wire sensor, reset the ECU learning mode by using software/cable (nissan datascan, conzult, etc) OR disconnecting the negative battery terminal overnight.

Thank you very much again DC Scotty, will be ordering very soon and posting results. Much appreciated.

Thanks for a great write up. I'm in the process of rebuilding a 1996 240sx I bought. I bought this car "in a box" with a S13 Blacktop SR20DET needing rebuilt. It has a Stainless Downpipe. It came with a single wire sensor in the downpipe and a 3 wire connector on the engine harness. and I thought after reading this. I might upgrade to the Bosch 4 wire. Will this sensor, and grounding, be a good upgrade for my build. After I complete the build and get the engine broken in. I plan on changing the ECU out to a stand alone AEM or similar unit. The guy I bought the car from had installed a set of BC Stage II cams and didn't retune the ecu. Leaned it out and hence how it ended up "in a box". I have installed a new set of rom in the ecu from Enthalpy, tuned for the BC Stage II cams. I have been reading up some on the "wide band sensors". Will the UEGO sensors, such as the one from AEM serve my immediate need for the stock ECU and my future plans to upgrade the ECU? If so I will go ahead with the AEM O2. and save myself $50 or $60. Also do the UEGO senors need to be grounded in the manner discussed to eliminate any potential differences. I'm sure you guys are aware that is what is being detected by all the good testing DC Scotty is performing. Any voltage detected, either AC or DC is a difference in potential. That is why the best reading is obtained when referenced to the ECU grounds. Since the ECU is grounded at the intake. That is the best ground for ANY EQUIPMENT which the ECU will reference. And the closer to the ECU grounds the better. ALL connections will have some resistance, along with different metals. The more connections and the further they are from the ground of the ECU the greater the potential difference, AKA voltage. The ECU could interpret this difference as a reading for any equipment being referenced. That's my Humble Opinion and 2 cents worth. Any help and advice I would greatly appreciate. I'm kinda new to the Tuning Scene but not the electrical and mechanical aspects.

is it possible to use any other 4 wire o2 Sensor or, musst it be special for the SR20DE ?