RB20DET O2 Sensor Help

[Headbanger]

So I need to pass emissions test. I failed horrendously, which I'm assuming is from running rich, which is what the guy at the shop suggested.

Now, I have an appointment for a complete diagnostic to figure out the issue, which is going to run me ~$150. If I'm going to spend all that money for them just to say it's the sensor, I'd rather replace the sensor, pay for another e-test and hopefully pass.

Now, what I've found on here in my research is that it's the same as a 300zx TT sensor.

The only sensor I have is on the turbo elbow


Since the Z32 sensor is for a cat, would it still work for me?
I did not do my engine swap, so I don't know if there should be a sensor elsewhere. I'm no mechanic, but my understanding is OBDI is only one O2 sensor right?

[Nismo_line]

yes that is the 02 sensor in your picture. i dont believe the 300zx sensor is in the cat but i could be wrong and yes the z32 sensor will work.

[Headbanger]

Thank you very much!

Napa website says "Front of converter". So I guess that could just mean before the cat.

[h4X6]

its a 300zx driver side o2 sensors....


i got one for sale

[Headbanger]

You're a tad bit far since I'm in Ontario lol Thanks though

[Skym]

Sensor behind the turbo is the stock narrowband (0-1V) o2 sensor. It's placed there because it reacts quicker to changes in A/F ratio. But it can fail earlier due to getting fouled. The o2 sensor should be checked, replaced if necessary every 40,000-60,000km. If o2 sensor hasn't been changed, change it.

When o2 sensor fails (fouled) it becomes lazy to switch between 0v (lean) and 1V (rich). Basically o2 sensor makes ECU make engine run lean for too long or rich for too long which uses more fuel and pops flames from exhaust (popping sound from exhaust). Another symptom is idle rpm can go up (lean) and rich (down).

Sensor down exhaust further, that plugs into cat is the cat overheat sensor. When cat blocks and exhaust temps reach over 800 degrees that sensor activates the cat overheat light on dash. If you pull sun visor down on drivers side, you'll notice writing in Japanese that I think says go to Nissan Dealership when cat overheat light lights up on dash. Cat overheat light is also the engine check light.

Sometimes the cat overheat sensor can be mistaken as a o2 sensor, as before tuning ECU they plumb a wideband 02 sensor (0-5V) into exhaust near cat (weld in a bung, etc). It's supposedly more accurate in that position, sensor last's longer, but it reacts slower to sudden changes in A/F ratio.

[Headbanger]

I get a lot of pops once my exhaust is hotter, usually they happen while shifting at about 4000rpm. Engine also tends to have a high idle until at least running temps. The other night after about a 100km drive on the highway I pull into my driveway and it was still idling at about 1400. Going to order one this week.

[Skym]

Running rich sounds like o2 sensor.

Constant higher idle could mean MAF has failed or dirty (remove and clean hotwire inside MAF with CRC MAF cleaner). When MAF failed on my car it would idle at around 1500rpm when cold, hot (didn't drop) and had MAF error code on ECU. Replaced MAF with good second hand MAF, problem solved.

Sometimes when stopping and get a higher idle, it can be due to a intake airleak on throttlebody intake hose joiner. Tighten intake hose clamps on intake hose joiner between throttlebody and intake pipe over top of engine and see if it goes away. Sometimes the stock rubber intake hose joiner goes hard and it doesn't seal properly.

It's normal for rpm to be around 1300rpm (sometimes higher in colder conditions) when engine is cold and drop to around 650rpm when warm. That's part of the normal warmup procedure on ECU.