well i found the connections for the front 02 sensors and cleaned those plugs off. i cleared the code and reset the idle air volume. its running decent, but the flat sounding exhaust note and loss of power are still surfacing every once and a while. i am tempted to put it back to stock and see if the code comes back. if so, on to the dealer.

 

UPDATE: I am at 600 miles plus after fixing exhaust leaks no CEL.

 

well the code has gone away after cleaning all the connections....BUT the 0420 code is still there. I believe the culprit is exhaust leaks at the flanges, so tomorrow i am ordering new gaskets....
part numbers-
20691-Z33002 for the upper flange
20692-Z33001 for the lower flange


and for safe measure i am going to add a small amount of exhaust gasket maker to the o2 threads since they were damaged some when removing them from the stock catalyst pipes.

 

guess i am the only one trying things to solve it.

I installed new gaskets and sealed up the o2 sensor threads with the gasket maker. car sounded and ran better for about 300 miles. then the p0420 code came back, and it had that intermittent crap exhaust note and loss of power again.

im bout ready to sell this piece

 

You're definitely not the only one trying to solve this. I just got back from a month of military training, so I'm back to working on this stupid issue. My latest theory has to do with the exhaust cam/valves. I remember looking on Cipher and seeing each side running with slightly different values (+/- 0.5). I need to go back and look at it, but I'm hoping this might be a sign of something.

On top of that, you have an 08 if I'm not mistaken, and I have an 06. The 06+ incorporated variable exhaust valve timing, so that could explain why we don't see earlier model cars having this issue.

At any rate, it's just a thought, and I figured it's worth throwing out there seeing how collectively, we've tried just about everything else. Possibly a bad solenoid for the exhaust cams causing one to run with a slight delay (thus creating a lean/rich condition in one bank)? What do you think?

 

yea i have found myself looking towards either the exhaust camshaft position sensors or the solenoids or the oil pressure driving the solenoids.

i still want to say its them, but i have had quite a few people post up in another thread about the stumbling/stuttering on start up. in there numerous others have the occasional stumbling and stuff like us while driving.

Thread->Sputtering during warmup

after receiving their recent input in that thread i am leaning to the throttle bodies as suspect. they point to one of the throttle bodies having an issue right at the changeover of going from "cold start" mode into "operation temp" mode. it always stumbles around 2minutes into the drive and can last for up to a few minutes....same as my own symptoms.

they state that its an issue thats been around since the 02 maximas. its an issue that is within the throttle body(drive by wire). and our symptoms match with their own. its almost like at points in the warm up/cold start cycles, the throttle body is no where near where its supposed to be. so the car will run really rich and timing will be adjusted to try and compensate for the a/f mix. it really kind of fits the big picture.

i wanna call up my buddy with his 370z or another with an 07 g35 sedan and swap Throttle bodies with either to confirm or deny
.

 

Ok I have installed the Nismo headers on my 06 roadster and now have the P2A03_(82) code. I am assuming that the cause is an exhaust leak as car runs fantastic without any issues. I will be subscribing to thread and if any see my thinking as faulty put me in the right direction.

One other thing. My CEL will only pop on under hard acceleration plus 5000+ acceleration.

 

That sounds a lot like what I would expect from a leak. With mine, the problem pops up under light load driving at relatively low rpms, which is completely different from what you're experiencing. The fact that with yours, it only happens under heavy load and high rpms makes me think that it's directly related to the nature of the flow of the exhaust and how a supposed leak is affecting it. I'd get under the car and check the bolts or at least look for carbon residue around the areas where the parts mate.

 

I would think that a problem with the throttle body would affect both banks equally. That, and I would think it would result in basic compensation for a rich or lean condition, not an addition of fuel to a condition already reading rich...? Maybe I'm not understanding something?

 

Thanks for the reply. I took a quick look under the car and could see no leaks and no residue as of yet but possible cracked HFC though I can hear no leak from up top. Will continue search today.

 

I have some extra parts and time so couple questions. IS THE CODE P2A03 the drivers side bank or the passenger side? Also are the 02 sensors the same for a 2003 as for a 2006? So far parts search says they are.

 

are you aware that there is a tsb for the "z" fuel line, they need to drop subframe replace all the soft fuel line and and filler neck.... that could be why your smelling fuel

 

nope didn't realize

Update:

Don't know if this will solve the CEL but there is no doubt the cat was cracked

 

A link for that would be awesome.

 

I have the VQ35HR.....two throttle bodies....so one side is being affected.

Im still lost with this problem. its frustrating.



heres a list of tsb's for ya
2006 Nissan 350Z TSB's

 

I have exactly the same voltage gap: https://my350z.com/forum/vq35hr/3078...arm-up-24.html

So, if it's the same thing for everyone, I assume it's normal ?

When I see all of us with the same issue, I really don't unserstand why Nissan do nothing for us ?

 

I just started throwing this code 2 weeks ago and its really driving me crazy. I used to have a 350Z but now I drive an Altima SE-R and there isn't any help being offered at nissanclub. Seems like its a rare issue for Altimas and I'm just that lucky. As far as pertinent mods go I've got an intake, HFCs, and a catless y-pipe. The light has been coming on sooner and sooner after trying to check for problems. Most recently 24 miles. I don't have any exhaust leak sounds or smells under my hood but I do have an incredibly rich smelling exhaust combined with an almost miss/stumble every once in a while. I do suspect failing injectors but as I've read here that can't be the only problem. P2A03 is the only code coming up when I scan. After running sea foam through my current tank my fuel mileage seems to not be as effected as it was before. My previous tank I only got 24 mpg and now its back up to 29 and change but I'm still throwing the code. I've checked that all of my exhaust joints are tight. With as rich as it smells sometimes I'd think that I could smell it under the hood if I had a leak. Not to mention that my light always comes on when I'm cruising 70 down the interstate. The most noticeable symptom that I have this code is that I'm down on power. My local dealership legitimately sucks at life (they missed a drinking straw size hole in my rear precat for 40k) so I'm looking for any help I can get. In the meanwhile if I get anywhere with my issue I will pass it along.

 

Don't know if this will help you guys but when my car had that big hole in my rear precat the car didn't even throw a code.

 

so i just had this same code pop up on me last night (p2a03). I have an 08 with an injen intake, berk tp, and a greddy evo II catback. prior to this i was throwing a code for the secondary o2 sensors. I did the non fouler trick to those and also packed a little steel wool in the non fouler to "suffocate" those o2's more (i was told others on the forum use steel wool in the secondary o2 bungs in order to trick the o2's). However, I think I may have suffocated them too much. if the computer reads one then the other and compares the two, then is it possible that it sees way less air flow on the secondaries and is just dumping fuel?

saturday ill pull the steel wool out and check for exhaust leaks and see if that helps.

also, the car smells like its running VERY rich. if the a/f is just way off, causing this code to pop up and i dyno tune the car getting the a/f back where it needs to be, will that be enough to keep the cel off if the programmer cant turn off codes from appearing?

 

The secondary O2 sensors (the ones in the cat section) are used only for emissions purposes. The wideband sensors in the primary section (in the exhaust manifold) are what the ECU is using to read and adjust fuel settings. So, no, that's not possible. Unless those sensors are throwing codes, you don't need to worry about having suffocated them too much or anything to that effect. First things first, check for exhaust leaks.