sontakke

When you clear the code, all of the self-test results are erased also. It takes a "while" to complete all of the on-board self-tests. Nobody will tell you exact test completion criteria but it does take some number of trips and some days before those tests will complete or if you are unlucky the code will be back.

The most important part of state inspection using OBD-II is that if either the light is ON or if the on-board tests are not completed, you do NOT pass the state inspection.

Don't reset the light and drive to the inspection station. It does not work. I found it hard way :-(

- Vikas

mn313

Im having the same problem with my 2000 SE when i have my computer read its also saying Catalytic Converter Deficiency bank one so i was told to change the first O2 sensor, i change the one on the manifold when u open the hood. but the light is still on. Im not to sure whether or not its on because i have a High Flow Cat on my car or not. Im am going to try and change my plugs see what happens if you have any other suggestions please let me know.

drewp

To all with P420 code, I went to the dealer and got my 2001 Maxima fixed under emission warranty (8yrs/ 80,000 miles)!
P.S. different dealers have different say about it, so try different dealership if one says it's not covered under warranty!
Good Luck!

CCS2k1Max

iTrader: (2)

What dealer fixed your PO420 code under the 8/80 emissions warranty? How did they fix it, changing the bank 1 front O2 sensor? My stealer wants to charge $105 diagnostics fee but if it's the sensor, they say it's not covered. I'm getting tired of resetting the damn MIL.

remembermorriso

I ran that code on my max about a month ago... So I took it to the dealership they replaced my cat but I sold the new one and just punched out the old one, and the code never went away. So I'm feeling your pain. I just replaced plugs so hopefully that will solve it. Id hate having to replace o2 sensors.

blackjackmark

I too got mine fixed under the 8/80 emissions warranty...but had to escalate it to Nissan corporate to get it fixed. Once Nissan corporate heard it was the P0420, they immediately approved the fix...no (further) hassle! (though I shouldn't have had to hassle with it in the first place..according to the tech at corporate, he said that some dealers misinterpret the manual). If the manual is that hard to interpret, why doesn't corporate change the wording!

BewstAdd1ct

wow... sooo... if you guys have a p0420/0430, its a catalyst efficiency fault, as long as the PCM is functioning properly (and properly updated), the catalyst is bad, OR you may have an exhaust leak... but its usually the cat. usually for the catalyst readiness test to run both o2 sensors have to be working.

leoniv

Pulled the same P0420 code yesterday. Didn't happen until I filled up at a gas station so I want to blame it on bad gas. Called the stealership and they said repair is covered under warranty if it's the ECM, cat, combination of both, or O2 sensors if they fail in conjuction with the ECM and/or cat. If it's just the O2 sensors that are bad, I have to pay. They want $95 just to diagnose the problem (don't have to pay it if it's covered). Kinda stuck b/c don't want to pay them the $95 if it turns out to be just the sensors, but then again don't want to pay nearly that much to a 3rd-party if it's covered. Curse Nissan.

BewstAdd1ct

o2s have to be working (and pass ready status) in order to set a p0420. take it to the dealer.

vizslak7

P0430 & PO430 are Pre Cat O2 Sensors and generally are Bogus Codes. The best way to deal with them, as I have, is to install a O2 Sensor Simulator (Dual Channel) from O2simulator.com.
JS

Larrio

iTrader: (10)

the ecu flash is designed to only work with 2001 maximas, which are all cali-spec. Its actually listed as a TSB at www.nissan-techinfo.com

BewstAdd1ct

umm, p0420/0430 are catalyst efficiency faults, not o2 sensor codes.

NismoMaxm

so how can one fix the PO420??ive got it and people are saying its a TSB and can be fixed if under 80k??Bew check my accel post aswell. gave some news.

BewstAdd1ct

ckd and replied.

heres the p0420 bulletin:


----------------------
Classification:
EC00-024a

Reference:
NTB00-070a

Date:
March 15, 2001

2000 - 2001 MAXIMA MIL "ON" WITH DTC P0420 STORED - THREE WAY CATALYST FUNCTION

This amended version of NTB00-070 updates the Applied Vehicles, Service Information, and Service Procedure Sections of the bulletin. Please discard all paper copies of NTB00-070.

APPLIED VEHICLES:
2000 - 2001 Maxima (A33) - Except 2000 Maximas with Federal Emissions Specification

SERVICE INFORMATION

If an applied 2000-2001 Maxima has a MIL "ON" with DTC P0420 (Three Way Catalyst Function) stored in the ECM, it may be the result of an internal ECM Program Misdiagnosis.

The catalyst should not be replaced. This bulletin provides updated ECM data to reprogram the vehicle's ECM to correct the condition.

This bulletin replaces NTB00-070 which should be discarded as noted above. The ECM reprogram contained in this bulletin is different than the reprogram described in the earlier bulletin. In addition, it is not required to perform the P0420 DTC confirmation test after reprogramming has been removed.







Use the diagnosis/repair flow chart shown and the appropriate Service Procedure steps provided in this bulletin to diagnose and repair this incident, if it should occur, regardless of whether or not the vehicle was previously repaired in accordance with the earlier bulletin.

These are the ONLY approved repair procedures for this incident. If the vehicle falls within this bulletin range, a claim to Nissan for the repair of this incident may be denied if the repairs are not performed exactly as outlined in this bulletin.

CLAIMS INFORMATION







Submit a Primary Failed Part (PP) line claim using the claims coding table as shown.
------------------------
Service precedure
-----------------------

Bulletin Applicability

Determine if this bulletin applies to the vehicle:







1. For 2000 Maxima vehicles, check the Emissions Certification Label on the underside of the engine hood (see Figure 1). Is the certificate for California emissions?

^ If the certificate is not for California emissions, this bulletin does not apply. Use the Service Manual DTC P0420 Procedures to further diagnose and repair.

^ If the certificate is for California emissions, proceed to ECM Part Number Identification and Update.



ECM Part Number Identification and Update







1. Determine the vehicle's ECM Part Number. The ECM P/N is found on top of the CONSULT-II self-diagnosis printout (see Figure 2), or by CONSULT ECM P/N Selection.








2. Compare the vehicle's ECM P/N to those shown under Current ECM P/N in Chart A shown:

^ If the vehicle's ECM P/N does not match one of those listed in Chart A, Current ECM P/N column; this bulletin does not apply. Use the Service Manual DTC P0420 Procedures to further diagnose and repair.









^ If the vehicle's ECM P/N does match one of those listed in Chart A, Current ECM P/N column; perform ECM reprogramming to update the ECM data to the new P/N. ASIST users refer to Attachment A in this bulletin.
---------------------------


basically if youre under 8/80, the PCM should be reprogrammed, and if the cat is indeed failed, it should be taken care of too...

NismoMaxm

ok so since i havent had mine redone and my cat is failed. what do i do, just go to my nissan dealership and tell them what??

BewstAdd1ct

if youre under 8/80, tell them theres an exhaust rattle, the ck engine light is on and nissan told you that you have a warranty on your catalytic converter and that your PCM should be reprogrammed under warranty.

dont pay or sign for checkout time.

Maximized Jiggs

iTrader: (1)

Hey guys, my GF just bought a 2000 maxima and after the first couple of days of owning it we have the same freaking problem as you guys. The light is on but the car drives great. I dont know what to do but I like that 02simulator idea. Can any one confirm this? I am going to order one if this WILL cure this problem. The car has 88k miles so the car wont be covered, too bad.

BewstAdd1ct

you have the same code?

Maximized Jiggs

iTrader: (1)

Yes, P0420. So how many of you resolved this with the O2 Simulator?

BewstAdd1ct

probably just as many who have bought an aftermarket cat.

a cat gets you passing an exhaust based emissions test wheras a simulator doesnt

sontakke

Has anybody dealt with Ira Nissan of Tewksbury, MA for fixing P0420 under 8/80 warranty? This seem to be a relatively small place with single service advisor.

I am having ON again and OFF again P0420 code for last 15 months. I am closing on the 80K miles and would like to get this monkey off my back as long as it is covered under the warranty.

- Vikas

sontakke

I am not able to connect to the TSB list from "theowensfamily.net" (also tried "theowensfamily.com"). Is this resource now gone?

I have found the reference which states that Cat, ECU and OBD are covered for 8/80K under Emission Warranty. Here is the URL for the document. Look at the 4th page where it is stated that catalytic converter is covered for 8/80K.

http://www.epa.gov/otaq/consumer/warr95fs.txt

I hope this helps somebody who needs to battle with the dealership.

By the way, here are the steps needed to diagnosis the P0420 P0430 code from the FSM (THANKS to whoever made that .PDF file available!)

Also note that this procedure does NOT list O2 sensors as culprit!! Don't let dealership try to sell you an un-needed O2 sensor for this problem.

DTC P0420 (BANK 1), P0430 (BANK 2) THREE WAY CATALYST FUNCTION
On Board Diagnosis Logic

SEF184UE
On Board Diagnosis Logic NFEC0783
The ECM monitors the switching frequency ratio of heated oxygen
sensor 1 (front) and heated oxygen sensors 2 (rear).
A three way catalyst (Manifold) with high oxygen storage capacity
will indicate a low switching frequency of heated oxygen sensor 2
(rear). As oxygen storage capacity decreases, the heated oxygen
sensor 2 (rear) switching frequency will increase.
When the frequency ratio of heated oxygen sensor 1 (front) and
heated oxygen sensor 2 (rear) approaches a specified limit value,
the three way catalyst (Manifold) malfunction is diagnosed.
Malfunction is detected when three way catalyst (Manifold) does
not operate properly, three way catalyst (Manifold) does not have
enough oxygen storage capacity.
Possible Cause NFEC0784
+ Three way catalyst (Manifold)
+ Exhaust tube
+ Intake air leaks
+ Injectors
+ Injector leaks
+ Spark plug
+ Improper ignition timing

saj07

Hi i just had mine done ay 74,000 all look at my post exactly what i did.

Print our of federal emmision law search in sticky
Print of TSB search in sticky
explaining to them just got of the phone with Nissan coorporate and consumer affairs department, They said P0420 is covered under 8/8k any arguments show them TSb then federal law all went very smooth after that 3 hours work new cat new gasket did not pay a dime

sontakke

Unfortunately, this time I got code P0171. This is the first time I have got anything other than P0420

Aaaaaaaaaarrrrrrrrrrrrrrgggggg

I am not familiar with P0171 at all :-( And I can not do the search of this forum to find the relevant topics, Looking at the FSM gives a list of possible problems but I would much rather see the actual experiences listed on this forum.

Any help would be greatly appreciated, especially list of topics discussing P0171 would be very helpful

- Vikas

BewstAdd1ct

maf sensor? lol.

check the fuel trims.

and who wrote the avobe thingy about the 0420. oxygen storage capacity?! gimme a break.

sontakke

Here are the fuel trim data looks very bad in the freeze frame LT for both the banks is 33.6 !!! I did not feel any change in the running of the car. I was driving gently and nothing seemed to be amiss.

Should I reset the code and see what happens? I am still on original MAF and coils. I change my air filters religiously.

By the way, that thing about oxygen storage capacity came straight from the factory service manual.

- Vikas

BewstAdd1ct

interesting, catalysts dont store oxygen, but thats okay.

the trims are 33% at just idle, or during cruise and accel also?

sontakke

Here is the freeze frame data:-

speed: 58mph
rpm: 2425
Engine load 26.3%
Temp 187 F

bank1,2 both Closed Loop
bank1 ST 5.5 LT 33.6
bank2 ST 1.6 LT 33.6

===============

Even afteri clearing codes, the Nissan seem to NOT reset the ST data!

At idle I was watching Bank1 ST -5 LT 18 and Bank2 ST -10, LT 25

During the drive around the block, LT was going in the 30 range. I don't think this is right. For last year or so, every time I had gotten P0420, the ST was hovering around 5. The oldest data that I have shows it to be in -3 range.

The MAF was 0.3 at idle and increased to 0.6 when I rev'd it little bit. Does that sound low?

It sure looks like running lean given that both LT are at max; so it has to be something which is common to both the cylinder banks. Either MAF (most likely) or low fuel pressure (bad regulator) or clogged sock in the tank.

About a week ago, the car had started hesitating on cold start between 1000 and 2000 rpm.

I wish I had saved the information on MAF repair/replacement

Thanks,
- Vikas

MaxBoost925

iTrader: (33)

yes, if all else fails, replace the MAF, it always works :-P (not really)

sontakke

Can you give me pointer to the procedure? I looked in the stickies but did not locate it on the list of the procedures.

Since mine is 2000, I should be able to replace only the sensor by removing the security torx screws. I purchased those bits from NAPA and have already squirted the rust penetrator on the screws. Any trick in removing the electrical connector?

Does Nissan still sells the sensor only part? The factory manual does NOT give a procedure on replacing either the MAF sensor or the tube assembly. I found the procedure in the Haynes manual but it tells me to take the aluminium band on the engine side and remove the four bolts on the intake box. The bottom bolts are impossible to reach without removing bunch of parts.

Am I approaching this wrong?

By the way, MAF sensor reading is within the spec. At idle it was 03 lb/min which is 2.15 gm/sec which right in the spec of 2-6 gm/sec

Thanks,
- Vikas

BewstAdd1ct

0.3 lb/min, or 0.3 volts?

you should see 1.2-1.8 volts at idle, also make sure you have a/c and all loads off, including electrical.

get a units reading on that and let us know, it does point to the MAF, id ck the fuel pressure just to make sure, but if it is the maf, then yes, T20 (IIRC) and replace the sensor.

Champ2433

iTrader: (9)

I just pulled a p0430 as well, 2000 se. I have a custom exhaust and a Cattman High Flow cat, still waiting on the headers. Anyway, I'm assuming I will need to switch back to my stock exhaust in order to possibly get the TSB for this? Haven't seen it mentioned anywhere so I figured I ask if anyone has had this particular problem. I know from experience that any custom work is a detriment when talking warranty issues.

Although it's probably a better idea to just get o2 sims, probably gonna need them when I install the headers anyway.

sontakke

It is 0.3 lb/min which is within the range but at the low end. I also have the log file of the OBD data for about 15 mile run. If mods will not get upset, I can post them here. I have converted into straight ascii file and decoded the parameters into ascii. What I did notice is that MAF readings do change but it is operating at the lower end of the acceptable range. The timing advances to over 40 during acceleration and the LTFT are staying in the +30 range. It goes down to +25 occassionaly. I even noticed a snapshot in which LTFT+STFT was over +40! That should have tripped the MIL but it did not.

I already ordered the MAF from Dave B. The price has gone up and it now $90 shipped. I will first try to clean the old one and see if it makes any difference.

Can you tell me why battery need to be disconnected? When the key is off, it should not be getting any power to the sensor. Is disconnecting the battery only way to reset the ECU parameters?

Thanks,
- Vikas

BewstAdd1ct

disconnect battery for what? i thought the '00-01s could reset like the 5.5s

can you display the reading in any other units. anywhere from 0.251-0.349 lb/min will give you the 0.3 reading, which is a bit on the ambiguous side for me. g/s would be really nice

sontakke

I was told by Dave B to disconnet the battery for overnight to reset the CPU. Is there a better way to reset the CPU? I could not find any specific fuse which provides the memory backup power for the ECU. Can you tell me the reset procedure?

Unfortunately, I am stuck with the units . My scanner software (BR3) does have option to switch the units. I will ask the developer if the car (and his software) can support more resolution.

I can mail you the ascii log if interested.

- Vikas

BewstAdd1ct

sure, Stage3fs01 [at] ya hoo dot com.

amitrana

I just bought a "00 SE and a couple days after i picked it up i got SES light. I went to autozone and pulled the codes and got P0420 then erased it. Since then 3 months ago, the light hasn't come back on again. My car is cali spec with 83K miles. I rad the TES and it seems like the P0420 is usually a computer problem (misdiagnosis). The car runs fine, but how can i confirm that it is not a mroe serious problem with the catalyt convertor? The light hasn't come back on. Should i take any action of jsut be happy the SES light isn't on.

thanks,
Jay

Woody

iTrader: (1)

the tsb states you should burn one and reset your ecu.

NitDawg

Good luck finally ran out for me. I have not had a single problem with my 2001 SE until 80800 miles when the SES light reared its ugly head. Pulled the code, P0420. Read all the posts in the forum, decided to get the computer reflashed at the dealer, still pulling the code. Replaced the cat, still got the code. Finally, the rear O2 sensors replaced and all is fine. 800 miles over the 80K, go figure. Can't really complain too much, however, about this car.

Maxima-Ness

So...is there a TSB for the 02-03 models with a P0420?