I have read many many posts on the subject of our cars throwing a P0430 code. My car failed emissions in VA because of this code. I have a 2000 cali spec with 104K miles

Less that 10K miles ago I replaced the plugs, coils, and MAF. I have not, however, had the ECU reprogramed (could that be the problem?)


What is the solution to this problem?

new 02 sensor(s)
replace preCat
install O2 simulator
reprogram ECU
unplug battery overnight and retest (garage is 1 mile from home)
replace intake with factory air box


Thanks for your help

 

Nissan recomends reprogram and O2 sensors first on that year if I recall, if it comes back y-pipe gets replaced.

 

At this point, since you need to get it re-tested soon, try getting a new O2 sensor or O2 sim and clearing the codes. If that doesn't work, look into finding a front precat for cheap. I know there've been several for sale in the Classifieds.

If you need local help with installs, parts, and whatnot, post up in the DC forum and I'm sure you'll find some help. I may have an extra single output O2 sim that you might be able to use as well, but I have to check.

 

Replacing the y-pipe does not replace the front pre-cat, which is what the P0430 is for.

 

I'm aware of that but that was the Nissan fix I belive there is a TSB on the procedure

 

Do you have a link to the TSB or know the TSB number?

The only TSB that I found for a 2000 Cali spec is for the P0420 code and that only involves reprogramming the ECU, and not replacing any pre-cats.

 

And btw, logically, that doesn't make sense to me either. Why would the y-pipe be replaced if the code isn't for the pre-cat in the y-pipe? Tell me if I'm missing something here.

 

can anyone else provide guidance?

 

im going through the same problem and I dont have a clear undertanding either

 

I just had P0430 and according to NISSAN the first step is the ECU Reprogram. They claim that the standard emissions levels change periodically due to age of car/engine and that the computer needs reprogrammed for the new level. They flashed the ECU and it was fine for 3 weeks and then the code came back.

After research and finding that others have replaced O2 sensors and the problem has gone away I went back and asked about the O2 sensors. The tech claimed the O2 sensors work together and the measure the downstream and upstream of the oxygen levels in the exhaust and if the levels are insufficient then you get the code. I asked them how they tested the O2 sensors and they measure them for voltage spikes that are outside of the normal working levels. If they get abnormal voltage then it might be a bad O2 sensor.

If the voltage levels are fine the O2 sensor should be fine and the ECM will call for the correct air to fuel mixture so the exhaust is within the acceptable level. If it isn’t within the acceptable level and the O2 sensor is good then the problem is with the Cat. Hope this helps, again, I am just passing along the info and it was pretty close to what I’ve read online.

Maybe you can check your O2 sensors according to this link.

http://www.unofficialbmw.com/all/eng..._o2sensor.html

 

I am not going to give any opinions on this P0420/P0430, though I will let the forumers know what I have done so far..

1) At 80K got P0430. Disconnected the red O2 sensor and hooked up O2 sim.
2) At 95K got P0138, heater circuit with last O2 sensor. Said to myself hell with it, finally got P0430 and could not get it off.
3) At 100K, replaced all O2 sensors with NGK sensors over the weekend, haven't seen any SES codes come back. My MPG is off the roof, touching 30 MPG.

I think it is premature to draw any conclusions.

 

install O2 sims

 

About how much does the ECU reprogram cost? I should have done it after replacing the coils, MAF and plugs so I feel that it should probably be the first step.

 

Hey,
How was your MPG before replacement? Was it normal or crappy? I have O2 sim for secondary, but even before that, my MPG started to die. I barely get 250 miles on the highway and not much power when the car warms up. I am thinking primary O2s, but not sure.
I don't have any codes for primary. Had P0430 many times - O2 fixed it.

 

$180.00 including the diagnostic fee.

 

If you've had P0430 many times and each time the O2 fixed it........ Don't you think that it might not have been the O2?

 

I usually got 24 MPG with mostly highway miles. Now with all the O2s replaced, I got 27 MPG, and when I drive below 2K RPM, I get 30MPG. 3MPG improvement after replacing the O2s and those crap **** P0420, P0430, P0135, P0138 hasn't come back.

I think it isn't the cat that was throwing these codes, I tapped on it and the honeycomb looked intact, nothing wiggling/shaking inside. The correct way to isolate the cat would have been temperature readings upstream and downstream, no backpressure to the engine.

 

Since its a pre-cat code and is emissions related, see if they will reprogram it for free under the 8/80 long term emissions defect warranty.

 

yes, but my car has over 100K miles

 

Darn. Was just wondering about that.

You sure you don't wanna just try swapping the O2 sensor first and save yourself the extra money? Or even use an O2 sim?

 

The only O2 sensor you can replace with a sim is the one after the last cat - correct? Replacing any other sensor with a sim would make the car run badly.

 

You are right that only the secondary O2 sensors can be simulated, but since his car is Cali spec, he has 2 downstream O2s, one after each pre-cat. In this case the front bank secondary is bad, so he could just simulate that O2 with a single output sim and get rid of the codes.

Fed spec cars are the only ones with an O2 sensor after the main/last cat.

 

T-Bone,

I posted my fix for this about 3 weeks ago. First, there isn't a TSB for the code, only a P0420 has a TSB. I had replaced my MAF without the reprogamming too.

The diags at the shop indicated two bad rear o2 sensors, when the po430 states there's a problem with Bank 2 which would imply only one o2 sensor may be problematic. The other bad o2 sensor never through a code and I'm unsure how long it may have been bad. So I chose to replace both o2 sensors and have the reprogramming done. I can only say that my car runs significantly better now. I'd get the diags done ($90) to determine if an o2 is bad. I'd also suggest reproogramming the MAF($100-150).

 

So I tested MAF sensor yesterday with voltmeter, turned out OK. Then, becuase I suspect bad MPG from O2 sensors, I unplugged one of the primary O2s while engine running. THere was no change in the way it ran, nothing. SHouldn't it change? Since ECU doesn't get reading out of it, the car would run lean or rich. Then I unplugged the other primary one, still the same. Gave it little gas, nothing obvious.
Weird..I also have a newer MAF.

 

According to the manual I have, p0430 refers to a problem in bank two where the front and rear O2 sensors are not giving a proper reading, and could mean:

Possible Cause

Three way catalyst (Manifold)
Exhaust tube
Intake air leaks
Injectors
Injector leaks
Spark plug
Improper ignition timing

If I had this problem the first thing I would do is replace the front an rear O2 sensors and see if that works (if your car has 100k miles, its really time to replace the sensors anyway).

Unless I am missing something, I don't think P0430 is part the TSB calling for an ECU reprogram:

http://maxima.theowensfamily.com/tsb/NTB02-051a.pdf

Hope this helps

 

Has anyone who had the P0420/0430 code also seen performance loss? I have a 2000 Fed spec and I would say the CEL is on about 50% of the time w/ the P0420. I noticed that when the CEL is on performance is weak (RPMs barely move after hitting 4K). But it runs fine when the CEL is off.

I was thinking it might be the cat but I doubt that would be an on again off again thing. Then I was thinking of the back 02 sensor but most say that has nothing to do w/ performance. I was going to replace the MAF and plugs but I didn't think those items would be on/off items w/ the CEL.

Also P0420 says right bank. Doesn't that depend on which way you are looking at the car? I've never replaced an O2 sensor before but which way should I be looking to identify the right bank?

I'm probably going to replace the plugs this summer (85K on car) but I'd rather not replace the MAF, all O2 sensors and the catalytic converter too.

 

Left bank = front bank
Right bank = rear bank

 

Thanks. Should I have the O2 sensor diagnostic done at a shop or dealer? How much are new sensors going to cost?

 

I think you should not spend $80 diagnosing the problem, spend that money replacing the O2 sensors. You have to replace them anyway if you are still on the OEMs and have 70-100K on them.

I bought NGK sensors from www.ngk.com and replaced them last week. No codes so far and boy there is a world of construction difference in these O2 sensors over the last 5 yrs (Bosch OEM vs NGK).

I bought 4 of them Cali spec for $330 and replaced them myself (local stealer quoted $170/sensor and DaveB quoted $105/sensor).

 

Any difference in performance or milage right after you put them in?

 

I got 3MPG addition with the O2s replaced and the vehicle is very responsive.

What I hated in my car before replacing the O2s was on uphill sections of the highway, it would act so stupid like it is dead and cannot catch the next gear inspite of flooring it, and if it did finally catch the gear it would jerk, hit 4K RPMs and fall back to 3K RPMs, just to move it from 60MPH to 70-80MPH.

Now it is smooth, it knows exact throttle position wrt gear changing, looks like the pretty new MAF, brand new O2 sensors and tranny are in sync!!!

 

OK, i am getting them. I've got 120k on original o2s. I am only going to replace primary, since rears are simulated. when my car warms up, it doesn't have any juice left in it. When I floor it in 2nd, its slow, specially in low end.
thanks for the comment.

 

So I should replace ALL FOUR O2 sensors at once? This is a D.I.Y. task, correct?

thanks

 

Try replacing o2's first. It's a DIY job, just a pain in the azz. If you order them from DaveB (meaning if you get the oem part) they are color coded (and expensive), just gotta follow the wires.

 

what about the NGK sensors? They're about $100 less for a set of 4.

 

I read that there was some wiring work to be done with those, but I don't remember. I bought the single o2 that I needed, and it was about 170 from DaveB if I remember correctly. PM if you need to search the .org

 

It sure is a DIY task, if you are prepared well,

1) Diagram of the exact locations of the sensors
2) Jacks
2) Autozone O2 sensor kit (get it for rental)
3) Start from the connector and go to the O2 sensor, to match replacement O2 sensors with the ones on the vehicle. The sensors all look the same but are different wrt lengths and end connectors, which distingishes them.
4) Zip tie the O2 wires away from exhaust manifold/hot surfaces correctly.
5) Patience since it takes close to 2 hrs to do the job. FYI, the last sensor (black wired) is tough to access.

 

There was no rewiring needed. The sensors came with the connectors and the length of wires exact to the OEM ones with the requisite # of zip ties. Just remove the old one and put in the new NGK ones. Enjoy!!!

 

Still wondering if I should order FOUR new sensors? Do all of them go bad over time? I'm at 105,000 miles.

 

Holy geez! I am so buying new NGK o2 sensors. I'll get P0138 if I drive the car hard. As in keeping the RPMs in the 4k range. Then after I get P0138 and I drive normal, RPM under 4K it goes away in about a day.

Nissan knows about that and the procedure is to replace both REAR oxygen sensors and have the ECU flashed to relax the standard for setting that code.