So this morning the MIL came on, so I came home and got my OBD2 reader for my phone and took a look.

The code is P0430 which is (according to obd-codes.com) for Nissan, Catalytic Converter - Bank 2 - Efficiency Below limit, I have the freeze-frame data and it is as follows:


Fuel system 1/2 status: 2
Calculated Load Value: 32.55%
Engine Coolant Temp: 195.8F/91C
Short Term Fuel Trim Bank 1: -3.12%
Long Term Fuel Trim Bank 1: 10.16%
Short Term Fuel Trim Bank 2: 0%
Long Term Fuel Trim Bank 2: 7.03%
Engine RPM: 1962.5 RPM
Speed: 52.2 mph
Throttle position %: 6.27%

not sure if its all the freeze frame data, but it does give the fuel trims. The long term on Bank 1 is out of spec (+-10% right?), but according to the code Bank 1 isnt the problem, bank 2 is, and the only thing strange I find on Bank 2 is that the short term is on perfect 0%.

I noticed when the car was idling, Bank 1 Long term would not budge from 10.16%. It just continuously sat there, which I find strange.

Car has 199,800 miles. O2 sensors have never been changed (probably should of done that when we changed the motor 6K miles ago) so Im thinking that could be the issue.

If I need to do any logged driving or give any more info let me know. Thanks in advance for the help!

 

Page 395-400

http://www.nicoclub.com/FSM/G35/Seda...5_Sedan/ec.pdf

Should be the same for all 03-06 sedans, although for future reference year of car would help to provide the correct fsm

I think you are overthinking the fuel trims. Those numbers don't look any different than what I've seen on my car. Something like an exhaust leak upstream of the O2 sensor can cause this as well. The FSM outlines some causes and things to check.

 

The +-10% is more important when it comes to the short-term fuel trim. I wouldn't worry about the long-term too much.

According to AllDataDIY:

Check the following:

Exhaust Leaks
Intake Leaks
Ignition Timing
Check fuel injector wiring at the ECM
Check ignition coils and spark plug
Check fuel injectors

I'd stick some SeaFoam in through your brake booster line and check your exhaust for leaks. That's what I did and it's the easiest way to find them, since it smokes like crazy. I found an intake leak with a DIY smoke machine I built.

 

Thanks for the SeaFoam tip on the exhaust leaks, very smart I never thought about doing that! Do you have a thread on your DIY smoke machine? If so can I have a link?

 

I don't have a link, but I build it with the following:

Wick for a lantern
Thin wiring
Some couplings for an AC compressor
Mineral Oil
Terminal connectors from RadioSHack
Alligator clips
Quart can from Home Depot

Drill holes in the top of the can, put the couplings in (air tight), wrap the wiring around the wick, connect each wire end to a terminal connecter, fill with mineral oil, and connect the alligator clips to your battery.

The mineral oil heats up and turns into smoke and I blew through one end to push the smoke out. If you smoke you can use a cigar or cigarette and blow into a vacuum line also, lol.

 

how about you post up some data from the o2 sensors?

if you have a graph, it should be a +/- wave instead of a flat line. A nice pattern.

 

So I did this... and here were my results on the G35:






G35 O2 results

um very different from the other car I used to compare it with (an old corolla)... (which may have an exhaust leak of its own because it has a weird sound to it)





Corolla O2 results

sorry for the large pictures...

 

any ideas? I have a feeling my scanner cant read either of the downstream O2 sensors for some reason... but they are reading positive volts (0.3 and 0.6 respectively) so idk... its just a flat line.

The upstream has more activity, but its not very much (not like the other car I compared it with anyway)

The very first day I posted this, I had reset the MIL and it has yet to come back on, but I just want to be sure we dont have a problem here.